Refactoring some codes around ingestion (#9274)

* Refactoring codes around ingestion:

- Parallel index task and simple task now use the same segment allocator implementation. This is reusable for the future implementation as well.
- Added PartitionAnalysis to store the analysis of the partitioning
- Move some util methods to SegmentLockHelper and rename it to TaskLockHelper

* fix build

* fix SingleDimensionShardSpecFactory

* optimize SingledimensionShardSpecFactory

* fix test

* shard spec builder

* import order

* shardSpecBuilder -> partialShardSpec

* build -> complete

* fix comment; add unit tests for partitionBoundaries

* add more tests and fix javadoc

* fix toString(); add serde tests for HashBasedNumberedPartialShardSpec and SegmentAllocateAction

* fix test

* add equality test for hash and range partial shard specs

core/pom.xml

@@ -324,6 +324,11 @@
       <artifactId>jetty-util</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>nl.jqno.equalsverifier</groupId>
+      <artifactId>equalsverifier</artifactId>
+      <scope>test</scope>
+    </dependency>
     <dependency>
       <groupId>com.google.errorprone</groupId>
       <artifactId>error_prone_annotations</artifactId>

core/src/main/java/org/apache/druid/indexer/partitions/DynamicPartitionsSpec.java

@@ -52,6 +52,12 @@ public class DynamicPartitionsSpec implements PartitionsSpec
     this.maxTotalRows = maxTotalRows;
   }
 
+  @Override
+  public SecondaryPartitionType getType()
+  {
+    return SecondaryPartitionType.LINEAR;
+  }
+
   @Override
   @JsonProperty
   public Integer getMaxRowsPerSegment()

core/src/main/java/org/apache/druid/indexer/partitions/HashedPartitionsSpec.java

@@ -123,6 +123,12 @@ public class HashedPartitionsSpec implements DimensionBasedPartitionsSpec
     return null;
   }
 
+  @Override
+  public SecondaryPartitionType getType()
+  {
+    return SecondaryPartitionType.HASH;
+  }
+
   @Nullable
   @Override
   @JsonProperty

core/src/main/java/org/apache/druid/indexer/partitions/PartitionsSpec.java

@@ -41,6 +41,9 @@ public interface PartitionsSpec
   String MAX_ROWS_PER_SEGMENT = "maxRowsPerSegment";
   int HISTORICAL_NULL = -1;
 
+  @JsonIgnore
+  SecondaryPartitionType getType();
+
   /**
    * Returns the max number of rows per segment.
    * Implementations can have different default values which it could be even null.
@@ -55,28 +58,6 @@ public interface PartitionsSpec
    */
   boolean needsDeterminePartitions(boolean useForHadoopTask);
 
-  /**
-   * '-1' regarded as null for some historical reason.
-   */
-  static boolean isEffectivelyNull(@Nullable Integer val)
-  {
-    return val == null || val == HISTORICAL_NULL;
-  }
-
-  /**
-   * '-1' regarded as null for some historical reason.
-   */
-  static boolean isEffectivelyNull(@Nullable Long val)
-  {
-    return val == null || val == HISTORICAL_NULL;
-  }
-
-  @Nullable
-  static Integer resolveHistoricalNullIfNeeded(@Nullable Integer val)
-  {
-    return isEffectivelyNull(val) ? null : val;
-  }
-
   /**
    * @return True if this partitionSpec's type is compatible with forceGuaranteedRollup=true.
    */
@@ -101,4 +82,26 @@ public interface PartitionsSpec
    */
   @JsonIgnore
   String getForceGuaranteedRollupIncompatiblityReason();
+
+  /**
+   * '-1' regarded as null for some historical reason.
+   */
+  static boolean isEffectivelyNull(@Nullable Integer val)
+  {
+    return val == null || val == HISTORICAL_NULL;
+  }
+
+  /**
+   * '-1' regarded as null for some historical reason.
+   */
+  static boolean isEffectivelyNull(@Nullable Long val)
+  {
+    return val == null || val == HISTORICAL_NULL;
+  }
+
+  @Nullable
+  static Integer resolveHistoricalNullIfNeeded(@Nullable Integer val)
+  {
+    return isEffectivelyNull(val) ? null : val;
+  }
 }

core/src/main/java/org/apache/druid/indexer/partitions/SecondaryPartitionType.java

@@ -0,0 +1,50 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexer.partitions;
+
+/**
+ * In Druid, ingested data are primarily partitioned based on time range (@link GranularitySpec#getSegmentGranularity),
+ * and then secondly partitioned based on the given {@link PartitionsSpec}. This enum lists all supported types for the
+ * secondary partitioning.
+ */
+public enum SecondaryPartitionType
+{
+  /**
+   * Linear partitioning partitions segments in the same time chunk based on their size or number of rows in them.
+   *
+   * @see DynamicPartitionsSpec
+   * @see org.apache.druid.timeline.partition.NumberedShardSpec
+   */
+  LINEAR,
+  /**
+   * Hash partitioning partitions segments in the same time chunk based on the hash value of the partition dimensions.
+   *
+   * @see HashedPartitionsSpec
+   * @see org.apache.druid.timeline.partition.HashBasedNumberedShardSpec
+   */
+  HASH,
+  /**
+   * Range partitioning partitions segments in the same time chunk based on the value range of the partition dimension.
+   *
+   * @see SingleDimensionPartitionsSpec
+   * @see org.apache.druid.timeline.partition.SingleDimensionShardSpec
+   */
+  RANGE
+}

core/src/main/java/org/apache/druid/indexer/partitions/SingleDimensionPartitionsSpec.java

@@ -138,6 +138,12 @@ public class SingleDimensionPartitionsSpec implements DimensionBasedPartitionsSp
     return targetRowsPerSegment;
   }
 
+  @Override
+  public SecondaryPartitionType getType()
+  {
+    return SecondaryPartitionType.RANGE;
+  }
+
   @JsonIgnore
   @Override
   @NotNull

core/src/main/java/org/apache/druid/timeline/partition/HashBasedNumberedPartialShardSpec.java

@@ -27,20 +27,22 @@ import javax.annotation.Nullable;
 import java.util.List;
 import java.util.Objects;
 
-public class HashBasedNumberedShardSpecFactory implements ShardSpecFactory
+public class HashBasedNumberedPartialShardSpec implements PartialShardSpec
 {
+  public static final String TYPE = "hashed";
+
   @Nullable
   private final List<String> partitionDimensions;
-  private final int numPartitions;
+  private final int numBuckets;
 
   @JsonCreator
-  public HashBasedNumberedShardSpecFactory(
+  public HashBasedNumberedPartialShardSpec(
       @JsonProperty("partitionDimensions") @Nullable List<String> partitionDimensions,
-      @JsonProperty("numPartitions") int numPartitions
+      @JsonProperty("numPartitions") int numBuckets
   )
   {
     this.partitionDimensions = partitionDimensions;
-    this.numPartitions = numPartitions;
+    this.numBuckets = numBuckets;
   }
 
   @Nullable
@@ -50,27 +52,28 @@ public class HashBasedNumberedShardSpecFactory implements ShardSpecFactory
     return partitionDimensions;
   }
 
-  @JsonProperty public int getNumPartitions()
+  @JsonProperty("numPartitions")
+  public int getNumBuckets()
   {
-    return numPartitions;
+    return numBuckets;
   }
 
   @Override
-  public ShardSpec create(ObjectMapper objectMapper, @Nullable ShardSpec specOfPreviousMaxPartitionId)
+  public ShardSpec complete(ObjectMapper objectMapper, @Nullable ShardSpec specOfPreviousMaxPartitionId)
   {
     final HashBasedNumberedShardSpec prevSpec = (HashBasedNumberedShardSpec) specOfPreviousMaxPartitionId;
     return new HashBasedNumberedShardSpec(
         prevSpec == null ? 0 : prevSpec.getPartitionNum() + 1,
-        numPartitions,
+        numBuckets,
         partitionDimensions,
         objectMapper
     );
   }
 
   @Override
-  public ShardSpec create(ObjectMapper objectMapper, int partitionId)
+  public ShardSpec complete(ObjectMapper objectMapper, int partitionId)
   {
-    return new HashBasedNumberedShardSpec(partitionId, numPartitions, partitionDimensions, objectMapper);
+    return new HashBasedNumberedShardSpec(partitionId, numBuckets, partitionDimensions, objectMapper);
   }
 
   @Override
@@ -88,14 +91,14 @@ public class HashBasedNumberedShardSpecFactory implements ShardSpecFactory
     if (o == null || getClass() != o.getClass()) {
       return false;
     }
-    HashBasedNumberedShardSpecFactory that = (HashBasedNumberedShardSpecFactory) o;
+    HashBasedNumberedPartialShardSpec that = (HashBasedNumberedPartialShardSpec) o;
-    return numPartitions == that.numPartitions &&
+    return numBuckets == that.numBuckets &&
            Objects.equals(partitionDimensions, that.partitionDimensions);
   }
 
   @Override
   public int hashCode()
   {
-    return Objects.hash(partitionDimensions, numPartitions);
+    return Objects.hash(partitionDimensions, numBuckets);
   }
 }

core/src/main/java/org/apache/druid/timeline/partition/LinearPartialShardSpec.java

@@ -23,21 +23,21 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 
 import javax.annotation.Nullable;
 
-public class LinearShardSpecFactory implements ShardSpecFactory
+public class LinearPartialShardSpec implements PartialShardSpec
 {
-  private static final LinearShardSpecFactory INSTANCE = new LinearShardSpecFactory();
+  private static final LinearPartialShardSpec INSTANCE = new LinearPartialShardSpec();
 
-  public static LinearShardSpecFactory instance()
+  public static LinearPartialShardSpec instance()
   {
     return INSTANCE;
   }
 
-  private LinearShardSpecFactory()
+  private LinearPartialShardSpec()
   {
   }
 
   @Override
-  public ShardSpec create(ObjectMapper objectMapper, @Nullable ShardSpec specOfPreviousMaxPartitionId)
+  public ShardSpec complete(ObjectMapper objectMapper, @Nullable ShardSpec specOfPreviousMaxPartitionId)
   {
     return new LinearShardSpec(
         specOfPreviousMaxPartitionId == null ? 0 : specOfPreviousMaxPartitionId.getPartitionNum() + 1
@@ -45,7 +45,7 @@ public class LinearShardSpecFactory implements ShardSpecFactory
   }
 
   @Override
-  public ShardSpec create(ObjectMapper objectMapper, int partitionId)
+  public ShardSpec complete(ObjectMapper objectMapper, int partitionId)
   {
     return new LinearShardSpec(partitionId);
   }

core/src/main/java/org/apache/druid/timeline/partition/NumberedOverwritePartialShardSpec.java

@@ -25,14 +25,14 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 
 import javax.annotation.Nullable;
 
-public class NumberedOverwritingShardSpecFactory implements ShardSpecFactory
+public class NumberedOverwritePartialShardSpec implements PartialShardSpec
 {
   private final int startRootPartitionId;
   private final int endRootPartitionId;
   private final short minorVersion;
 
   @JsonCreator
-  public NumberedOverwritingShardSpecFactory(
+  public NumberedOverwritePartialShardSpec(
       @JsonProperty("startRootPartitionId") int startRootPartitionId,
       @JsonProperty("endRootPartitionId") int endRootPartitionId,
       @JsonProperty("minorVersion") short minorVersion
@@ -62,7 +62,7 @@ public class NumberedOverwritingShardSpecFactory implements ShardSpecFactory
   }
 
   @Override
-  public ShardSpec create(ObjectMapper objectMapper, @Nullable ShardSpec specOfPreviousMaxPartitionId)
+  public ShardSpec complete(ObjectMapper objectMapper, @Nullable ShardSpec specOfPreviousMaxPartitionId)
   {
     // specOfPreviousMaxPartitionId is the max partitionId of the same shardSpec
     // and could be null if all existing segments are first-generation segments.
@@ -77,7 +77,7 @@ public class NumberedOverwritingShardSpecFactory implements ShardSpecFactory
   }
 
   @Override
-  public ShardSpec create(ObjectMapper objectMapper, int partitionId)
+  public ShardSpec complete(ObjectMapper objectMapper, int partitionId)
   {
     return new NumberedOverwriteShardSpec(partitionId, startRootPartitionId, endRootPartitionId, minorVersion);
   }

core/src/main/java/org/apache/druid/timeline/partition/NumberedPartialShardSpec.java

@@ -23,21 +23,21 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 
 import javax.annotation.Nullable;
 
-public class NumberedShardSpecFactory implements ShardSpecFactory
+public class NumberedPartialShardSpec implements PartialShardSpec
 {
-  private static final NumberedShardSpecFactory INSTANCE = new NumberedShardSpecFactory();
+  private static final NumberedPartialShardSpec INSTANCE = new NumberedPartialShardSpec();
 
-  public static NumberedShardSpecFactory instance()
+  public static NumberedPartialShardSpec instance()
   {
     return INSTANCE;
   }
 
-  private NumberedShardSpecFactory()
+  private NumberedPartialShardSpec()
   {
   }
 
   @Override
-  public ShardSpec create(ObjectMapper objectMapper, @Nullable ShardSpec specOfPreviousMaxPartitionId)
+  public ShardSpec complete(ObjectMapper objectMapper, @Nullable ShardSpec specOfPreviousMaxPartitionId)
   {
     if (specOfPreviousMaxPartitionId == null) {
       return new NumberedShardSpec(0, 0);
@@ -48,7 +48,7 @@ public class NumberedShardSpecFactory implements ShardSpecFactory
   }
 
   @Override
-  public ShardSpec create(ObjectMapper objectMapper, int partitionId)
+  public ShardSpec complete(ObjectMapper objectMapper, int partitionId)
   {
     return new NumberedShardSpec(partitionId, 0);
   }

core/src/main/java/org/apache/druid/timeline/partition/PartialShardSpec.java

@@ -19,38 +19,43 @@
 
 package org.apache.druid.timeline.partition;
 
+import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonSubTypes;
+import com.fasterxml.jackson.annotation.JsonSubTypes.Type;
 import com.fasterxml.jackson.annotation.JsonTypeInfo;
 import com.fasterxml.jackson.databind.ObjectMapper;
 
 import javax.annotation.Nullable;
 
 /**
- * Factory to be used to allocate segments remotely in the overlord.
+ * Class to contain all information of a {@link ShardSpec} except for the partition ID.
+ * This class is mainly used by the indexing tasks to allocate new segments using the Overlord.
  */
 @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "type")
 @JsonSubTypes({
-    @JsonSubTypes.Type(name = "numbered", value = NumberedShardSpecFactory.class),
+    @Type(name = "numbered", value = NumberedPartialShardSpec.class),
-    @JsonSubTypes.Type(name = "hashed", value = HashBasedNumberedShardSpecFactory.class),
+    @Type(name = HashBasedNumberedPartialShardSpec.TYPE, value = HashBasedNumberedPartialShardSpec.class),
-    @JsonSubTypes.Type(name = "numbered_overwrite", value = NumberedOverwritingShardSpecFactory.class),
+    @Type(name = "single_dim", value = SingleDimensionPartialShardSpec.class),
+    @Type(name = "numbered_overwrite", value = NumberedOverwritePartialShardSpec.class),
 })
-public interface ShardSpecFactory
+public interface PartialShardSpec
 {
   /**
-   * Create a new shardSpec based on {@code specOfPreviousMaxPartitionId}. If it's null, it assumes that this is the
+   * Creates a new ShardSpec based on {@code specOfPreviousMaxPartitionId}. If it's null, it assumes that this is the
-   * first call for the timeChunk where the new segment is created.
+   * first call for the time chunk where the new segment is created.
    * Note that {@code specOfPreviousMaxPartitionId} can also be null for {@link OverwriteShardSpec} if all segments
    * in the timeChunk are first-generation segments.
    */
-  ShardSpec create(ObjectMapper objectMapper, @Nullable ShardSpec specOfPreviousMaxPartitionId);
+  ShardSpec complete(ObjectMapper objectMapper, @Nullable ShardSpec specOfPreviousMaxPartitionId);
 
   /**
-   * Create a new shardSpec having the given partitionId.
+   * Creates a new shardSpec having the given partitionId.
    */
-  ShardSpec create(ObjectMapper objectMapper, int partitionId);
+  ShardSpec complete(ObjectMapper objectMapper, int partitionId);
 
   /**
-   * Return the class of the shardSpec created by this factory.
+   * Returns the class of the shardSpec created by this factory.
    */
+  @JsonIgnore
   Class<? extends ShardSpec> getShardSpecClass();
 }

core/src/main/java/org/apache/druid/timeline/partition/PartitionBoundaries.java

@@ -17,7 +17,7 @@
  * under the License.
  */
 
-package org.apache.druid.indexing.common.task.batch.parallel.distribution;
+package org.apache.druid.timeline.partition;
 
 import com.google.common.collect.ForwardingList;
 
@@ -25,6 +25,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
+import java.util.Objects;
 import java.util.stream.Collectors;
 
 /**
@@ -74,4 +75,31 @@ public class PartitionBoundaries extends ForwardingList<String> implements List<
   {
     return delegate;
   }
+
+  public int getNumBuckets()
+  {
+    return delegate.size() - 1;
+  }
+
+  @Override
+  public boolean equals(Object o)
+  {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    if (!super.equals(o)) {
+      return false;
+    }
+    PartitionBoundaries strings = (PartitionBoundaries) o;
+    return Objects.equals(delegate, strings.delegate);
+  }
+
+  @Override
+  public int hashCode()
+  {
+    return Objects.hash(super.hashCode(), delegate);
+  }
 }

core/src/main/java/org/apache/druid/timeline/partition/SingleDimensionPartialShardSpec.java

@@ -0,0 +1,141 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.timeline.partition;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import javax.annotation.Nullable;
+import java.util.Objects;
+
+public class SingleDimensionPartialShardSpec implements PartialShardSpec
+{
+  private final String partitionDimension;
+  private final int bucketId;
+  @Nullable
+  private final String start;
+  @Nullable
+  private final String end;
+  private final int numBuckets;
+
+  @JsonCreator
+  public SingleDimensionPartialShardSpec(
+      @JsonProperty("partitionDimension") String partitionDimension,
+      @JsonProperty("bucketId") int bucketId,
+      @JsonProperty("start") @Nullable String start,
+      @JsonProperty("end") @Nullable String end,
+      @JsonProperty("numBuckets") int numBuckets
+  )
+  {
+    this.partitionDimension = partitionDimension;
+    this.bucketId = bucketId;
+    this.start = start;
+    this.end = end;
+    this.numBuckets = numBuckets;
+  }
+
+  @JsonProperty
+  public String getPartitionDimension()
+  {
+    return partitionDimension;
+  }
+
+  @JsonProperty
+  public int getBucketId()
+  {
+    return bucketId;
+  }
+
+  @JsonProperty
+  @Nullable
+  public String getStart()
+  {
+    return start;
+  }
+
+  @JsonProperty
+  @Nullable
+  public String getEnd()
+  {
+    return end;
+  }
+
+  @JsonProperty
+  public int getNumBuckets()
+  {
+    return numBuckets;
+  }
+
+  @Override
+  public ShardSpec complete(ObjectMapper objectMapper, @Nullable ShardSpec specOfPreviousMaxPartitionId)
+  {
+    final int partitionId;
+    if (specOfPreviousMaxPartitionId != null) {
+      assert specOfPreviousMaxPartitionId instanceof SingleDimensionShardSpec;
+      final SingleDimensionShardSpec prevSpec = (SingleDimensionShardSpec) specOfPreviousMaxPartitionId;
+      partitionId = prevSpec.getPartitionNum() + 1;
+    } else {
+      partitionId = 0;
+    }
+    return complete(objectMapper, partitionId);
+  }
+
+  @Override
+  public ShardSpec complete(ObjectMapper objectMapper, int partitionId)
+  {
+    // TODO: bucketId and numBuckets should be added to SingleDimensionShardSpec in a follow-up PR.
+    return new SingleDimensionShardSpec(
+        partitionDimension,
+        start,
+        end,
+        partitionId
+    );
+  }
+
+  @Override
+  public Class<? extends ShardSpec> getShardSpecClass()
+  {
+    return SingleDimensionShardSpec.class;
+  }
+
+  @Override
+  public boolean equals(Object o)
+  {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    SingleDimensionPartialShardSpec that = (SingleDimensionPartialShardSpec) o;
+    return bucketId == that.bucketId &&
+           numBuckets == that.numBuckets &&
+           Objects.equals(partitionDimension, that.partitionDimension) &&
+           Objects.equals(start, that.start) &&
+           Objects.equals(end, that.end);
+  }
+
+  @Override
+  public int hashCode()
+  {
+    return Objects.hash(partitionDimension, bucketId, start, end, numBuckets);
+  }
+}

core/src/test/java/org/apache/druid/timeline/partition/HashBasedNumberedPartialShardSpecTest.java

@@ -0,0 +1,74 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.timeline.partition;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.collect.ImmutableList;
+import nl.jqno.equalsverifier.EqualsVerifier;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.util.Map;
+
+public class HashBasedNumberedPartialShardSpecTest
+{
+  private static final ObjectMapper MAPPER = new ObjectMapper();
+
+  @Test
+  public void testEquals()
+  {
+    EqualsVerifier.forClass(HashBasedNumberedPartialShardSpec.class)
+                  .usingGetClass()
+                  .withNonnullFields("partitionDimensions", "numBuckets")
+                  .verify();
+  }
+
+  @Test
+  public void testSerde() throws IOException
+  {
+    final HashBasedNumberedPartialShardSpec expected = new HashBasedNumberedPartialShardSpec(
+        ImmutableList.of("dim1", "dim2"),
+        3
+    );
+    final byte[] json = MAPPER.writeValueAsBytes(expected);
+    final HashBasedNumberedPartialShardSpec fromJson = (HashBasedNumberedPartialShardSpec) MAPPER.readValue(
+        json,
+        PartialShardSpec.class
+    );
+    Assert.assertEquals(expected, fromJson);
+  }
+
+  @Test
+  public void testJsonPropertyNames() throws IOException
+  {
+    final HashBasedNumberedPartialShardSpec expected = new HashBasedNumberedPartialShardSpec(
+        ImmutableList.of("dim1", "dim2"),
+        3
+    );
+    final byte[] json = MAPPER.writeValueAsBytes(expected);
+    //noinspection unchecked
+    final Map<String, Object> map = MAPPER.readValue(json, Map.class);
+    Assert.assertEquals(3, map.size());
+    Assert.assertEquals(HashBasedNumberedPartialShardSpec.TYPE, map.get("type"));
+    Assert.assertEquals(expected.getPartitionDimensions(), map.get("partitionDimensions"));
+    Assert.assertEquals(expected.getNumBuckets(), map.get("numPartitions"));
+  }
+}

core/src/test/java/org/apache/druid/timeline/partition/PartitionBoundariesTest.java

@@ -17,9 +17,11 @@
  * under the License.
  */
 
-package org.apache.druid.indexing.common.task.batch.parallel.distribution;
+package org.apache.druid.timeline.partition;
 
-import org.apache.druid.segment.TestHelper;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import nl.jqno.equalsverifier.EqualsVerifier;
 import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
@@ -74,8 +76,23 @@ public class PartitionBoundariesTest
   }
 
   @Test
-  public void serializesDeserializes()
+  public void serializesDeserializes() throws JsonProcessingException
   {
-    TestHelper.testSerializesDeserializes(TestHelper.JSON_MAPPER, target);
+    final ObjectMapper objectMapper = new ObjectMapper();
+    String serialized = objectMapper.writeValueAsString(target);
+    Object deserialized = objectMapper.readValue(serialized, target.getClass());
+    Assert.assertEquals(serialized, objectMapper.writeValueAsString(deserialized));
+  }
+
+  @Test
+  public void testGetNumBucketsOfNonEmptyPartitionBoundariesReturningCorrectSize()
+  {
+    Assert.assertEquals(2, target.getNumBuckets());
+  }
+
+  @Test
+  public void testEqualsContract()
+  {
+    EqualsVerifier.forClass(PartitionBoundaries.class).withNonnullFields("delegate").usingGetClass().verify();
   }
 }

core/src/test/java/org/apache/druid/timeline/partition/SingleDimensionPartialShardSpecTest.java

@@ -0,0 +1,58 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.timeline.partition;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import nl.jqno.equalsverifier.EqualsVerifier;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.IOException;
+
+public class SingleDimensionPartialShardSpecTest
+{
+  @Test
+  public void testEquals()
+  {
+    EqualsVerifier.forClass(SingleDimensionPartialShardSpec.class)
+                  .usingGetClass()
+                  .withNonnullFields("partitionDimension", "bucketId", "numBuckets")
+                  .verify();
+  }
+
+  @Test
+  public void testSerde() throws IOException
+  {
+    final SingleDimensionPartialShardSpec expected = new SingleDimensionPartialShardSpec(
+        "partitionKey",
+        3,
+        "start",
+        "end",
+        10
+    );
+    final ObjectMapper mapper = new ObjectMapper();
+    final byte[] json = mapper.writeValueAsBytes(expected);
+    final SingleDimensionPartialShardSpec fromJson = (SingleDimensionPartialShardSpec) mapper.readValue(
+        json,
+        PartialShardSpec.class
+    );
+    Assert.assertEquals(expected, fromJson);
+  }
+}

indexing-hadoop/src/test/java/org/apache/druid/indexer/IndexGeneratorJobTest.java

@@ -369,7 +369,14 @@ public class IndexGeneratorJobTest
                 new StringInputRowParser(
                     new JSONParseSpec(
                         new TimestampSpec("ts", "yyyyMMddHH", null),
-                        new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of("B", "F", "M", "Q", "X", "Y")), null, null),
+                        new DimensionsSpec(DimensionsSpec.getDefaultSchemas(ImmutableList.of(
+                            "B",
+                            "F",
+                            "M",
+                            "Q",
+                            "X",
+                            "Y"
+                        )), null, null),
                         null,
                         null
                     ),
@@ -553,12 +560,22 @@ public class IndexGeneratorJobTest
     List<ShardSpec> specs = new ArrayList<>();
     if ("hashed".equals(partitionType)) {
       for (Integer[] shardInfo : (Integer[][]) shardInfoForEachShard) {
-        specs.add(new HashBasedNumberedShardSpec(shardInfo[0], shardInfo[1], null, HadoopDruidIndexerConfig.JSON_MAPPER));
+        specs.add(new HashBasedNumberedShardSpec(
+            shardInfo[0],
+            shardInfo[1],
+            null,
+            HadoopDruidIndexerConfig.JSON_MAPPER
+        ));
       }
     } else if ("single".equals(partitionType)) {
       int partitionNum = 0;
       for (String[] shardInfo : (String[][]) shardInfoForEachShard) {
-        specs.add(new SingleDimensionShardSpec("host", shardInfo[0], shardInfo[1], partitionNum++));
+        specs.add(new SingleDimensionShardSpec(
+            "host",
+            shardInfo[0],
+            shardInfo[1],
+            partitionNum++
+        ));
       }
     } else {
       throw new RE("Invalid partition type:[%s]", partitionType);

indexing-service/src/main/java/org/apache/druid/indexing/appenderator/ActionBasedSegmentAllocator.java

@@ -25,6 +25,7 @@ import org.apache.druid.segment.indexing.DataSchema;
 import org.apache.druid.segment.realtime.appenderator.SegmentAllocator;
 import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
 
+import javax.annotation.Nullable;
 import java.io.IOException;
 
 public class ActionBasedSegmentAllocator implements SegmentAllocator
@@ -44,6 +45,7 @@ public class ActionBasedSegmentAllocator implements SegmentAllocator
     this.actionGenerator = actionGenerator;
   }
 
+  @Nullable
   @Override
   public SegmentIdWithShardSpec allocate(
       final InputRow row,

indexing-service/src/main/java/org/apache/druid/indexing/common/actions/LocalTaskActionClient.java

@@ -19,7 +19,6 @@
 
 package org.apache.druid.indexing.common.actions;
 
-import com.google.common.annotations.VisibleForTesting;
 import org.apache.druid.indexing.common.task.IndexTaskUtils;
 import org.apache.druid.indexing.common.task.Task;
 import org.apache.druid.indexing.overlord.TaskStorage;
@@ -27,15 +26,10 @@ import org.apache.druid.java.util.common.ISE;
 import org.apache.druid.java.util.emitter.EmittingLogger;
 import org.apache.druid.java.util.emitter.service.ServiceMetricEvent;
 
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.atomic.AtomicInteger;
-
 public class LocalTaskActionClient implements TaskActionClient
 {
   private static final EmittingLogger log = new EmittingLogger(LocalTaskActionClient.class);
 
-  private final ConcurrentHashMap<Class<? extends TaskAction>, AtomicInteger> actionCountMap = new ConcurrentHashMap<>();
-
   private final Task task;
   private final TaskStorage storage;
   private final TaskActionToolbox toolbox;
@@ -79,17 +73,9 @@ public class LocalTaskActionClient implements TaskActionClient
     final long performStartTime = System.currentTimeMillis();
     final RetType result = taskAction.perform(task, toolbox);
     emitTimerMetric("task/action/run/time", System.currentTimeMillis() - performStartTime);
-    actionCountMap.computeIfAbsent(taskAction.getClass(), k -> new AtomicInteger()).incrementAndGet();
     return result;
   }
 
-  @VisibleForTesting
-  public int getActionCount(Class<? extends TaskAction> actionClass)
-  {
-    final AtomicInteger count = actionCountMap.get(actionClass);
-    return count == null ? 0 : count.get();
-  }
-
   private void emitTimerMetric(final String metric, final long time)
   {
     final ServiceMetricEvent.Builder metricBuilder = ServiceMetricEvent.builder();

indexing-service/src/main/java/org/apache/druid/indexing/common/actions/SegmentAllocateAction.java

@@ -37,8 +37,8 @@ import org.apache.druid.java.util.common.granularity.Granularity;
 import org.apache.druid.java.util.common.logger.Logger;
 import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
 import org.apache.druid.timeline.DataSegment;
-import org.apache.druid.timeline.partition.NumberedShardSpecFactory;
+import org.apache.druid.timeline.partition.NumberedPartialShardSpec;
-import org.apache.druid.timeline.partition.ShardSpecFactory;
+import org.apache.druid.timeline.partition.PartialShardSpec;
 import org.joda.time.DateTime;
 import org.joda.time.Interval;
 
@@ -63,6 +63,8 @@ import java.util.stream.Collectors;
  */
 public class SegmentAllocateAction implements TaskAction<SegmentIdWithShardSpec>
 {
+  public static final String TYPE = "segmentAllocate";
+
   private static final Logger log = new Logger(SegmentAllocateAction.class);
 
   // Prevent spinning forever in situations where the segment list just won't stop changing.
@@ -75,7 +77,7 @@ public class SegmentAllocateAction implements TaskAction<SegmentIdWithShardSpec>
   private final String sequenceName;
   private final String previousSegmentId;
   private final boolean skipSegmentLineageCheck;
-  private final ShardSpecFactory shardSpecFactory;
+  private final PartialShardSpec partialShardSpec;
   private final LockGranularity lockGranularity;
 
   @JsonCreator
@@ -88,7 +90,7 @@ public class SegmentAllocateAction implements TaskAction<SegmentIdWithShardSpec>
       @JsonProperty("previousSegmentId") String previousSegmentId,
       @JsonProperty("skipSegmentLineageCheck") boolean skipSegmentLineageCheck,
       // nullable for backward compatibility
-      @JsonProperty("shardSpecFactory") @Nullable ShardSpecFactory shardSpecFactory,
+      @JsonProperty("shardSpecFactory") @Nullable PartialShardSpec partialShardSpec,
       @JsonProperty("lockGranularity") @Nullable LockGranularity lockGranularity // nullable for backward compatibility
   )
   {
@@ -102,7 +104,7 @@ public class SegmentAllocateAction implements TaskAction<SegmentIdWithShardSpec>
     this.sequenceName = Preconditions.checkNotNull(sequenceName, "sequenceName");
     this.previousSegmentId = previousSegmentId;
     this.skipSegmentLineageCheck = skipSegmentLineageCheck;
-    this.shardSpecFactory = shardSpecFactory == null ? NumberedShardSpecFactory.instance() : shardSpecFactory;
+    this.partialShardSpec = partialShardSpec == null ? NumberedPartialShardSpec.instance() : partialShardSpec;
     this.lockGranularity = lockGranularity == null ? LockGranularity.TIME_CHUNK : lockGranularity;
   }
 
@@ -148,10 +150,10 @@ public class SegmentAllocateAction implements TaskAction<SegmentIdWithShardSpec>
     return skipSegmentLineageCheck;
   }
 
-  @JsonProperty
+  @JsonProperty("shardSpecFactory")
-  public ShardSpecFactory getShardSpecFactory()
+  public PartialShardSpec getPartialShardSpec()
   {
-    return shardSpecFactory;
+    return partialShardSpec;
   }
 
   @JsonProperty
@@ -293,7 +295,7 @@ public class SegmentAllocateAction implements TaskAction<SegmentIdWithShardSpec>
             task.getGroupId(),
             dataSource,
             tryInterval,
-            shardSpecFactory,
+            partialShardSpec,
             task.getPriority(),
             sequenceName,
             previousSegmentId,
@@ -355,7 +357,7 @@ public class SegmentAllocateAction implements TaskAction<SegmentIdWithShardSpec>
            ", sequenceName='" + sequenceName + '\'' +
            ", previousSegmentId='" + previousSegmentId + '\'' +
            ", skipSegmentLineageCheck=" + skipSegmentLineageCheck +
-           ", shardSpecFactory=" + shardSpecFactory +
+           ", partialShardSpec=" + partialShardSpec +
            ", lockGranularity=" + lockGranularity +
            '}';
   }

indexing-service/src/main/java/org/apache/druid/indexing/common/actions/SegmentTransactionalInsertAction.java

@@ -27,8 +27,8 @@ import com.google.common.collect.ImmutableSet;
 import org.apache.druid.indexing.common.LockGranularity;
 import org.apache.druid.indexing.common.TaskLock;
 import org.apache.druid.indexing.common.task.IndexTaskUtils;
-import org.apache.druid.indexing.common.task.SegmentLockHelper;
 import org.apache.druid.indexing.common.task.Task;
+import org.apache.druid.indexing.common.task.TaskLockHelper;
 import org.apache.druid.indexing.overlord.CriticalAction;
 import org.apache.druid.indexing.overlord.DataSourceMetadata;
 import org.apache.druid.indexing.overlord.SegmentPublishResult;
@@ -238,8 +238,8 @@ public class SegmentTransactionalInsertAction implements TaskAction<SegmentPubli
     final Map<Interval, List<DataSegment>> oldSegmentsMap = groupSegmentsByIntervalAndSort(segmentsToBeOverwritten);
     final Map<Interval, List<DataSegment>> newSegmentsMap = groupSegmentsByIntervalAndSort(segments);
 
-    oldSegmentsMap.values().forEach(SegmentLockHelper::verifyRootPartitionIsAdjacentAndAtomicUpdateGroupIsFull);
+    oldSegmentsMap.values().forEach(TaskLockHelper::verifyRootPartitionIsAdjacentAndAtomicUpdateGroupIsFull);
-    newSegmentsMap.values().forEach(SegmentLockHelper::verifyRootPartitionIsAdjacentAndAtomicUpdateGroupIsFull);
+    newSegmentsMap.values().forEach(TaskLockHelper::verifyRootPartitionIsAdjacentAndAtomicUpdateGroupIsFull);
 
     oldSegmentsMap.forEach((interval, oldSegmentsPerInterval) -> {
       final List<DataSegment> newSegmentsPerInterval = Preconditions.checkNotNull(

indexing-service/src/main/java/org/apache/druid/indexing/common/actions/TaskAction.java

@@ -40,7 +40,7 @@ import org.apache.druid.indexing.common.task.Task;
     @JsonSubTypes.Type(name = "segmentListUnused", value = RetrieveUnusedSegmentsAction.class),
     @JsonSubTypes.Type(name = "segmentNuke", value = SegmentNukeAction.class),
     @JsonSubTypes.Type(name = "segmentMetadataUpdate", value = SegmentMetadataUpdateAction.class),
-    @JsonSubTypes.Type(name = "segmentAllocate", value = SegmentAllocateAction.class),
+    @JsonSubTypes.Type(name = SegmentAllocateAction.TYPE, value = SegmentAllocateAction.class),
     @JsonSubTypes.Type(name = "resetDataSourceMetadata", value = ResetDataSourceMetadataAction.class),
     @JsonSubTypes.Type(name = "checkPointDataSourceMetadata", value = CheckPointDataSourceMetadataAction.class),
     @JsonSubTypes.Type(name = "surrogateAction", value = SurrogateAction.class)

indexing-service/src/main/java/org/apache/druid/indexing/common/task/AbstractBatchIndexTask.java

@@ -24,8 +24,6 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Iterables;
 import org.apache.druid.data.input.FirehoseFactory;
 import org.apache.druid.indexer.TaskStatus;
-import org.apache.druid.indexer.partitions.HashedPartitionsSpec;
-import org.apache.druid.indexer.partitions.PartitionsSpec;
 import org.apache.druid.indexing.common.LockGranularity;
 import org.apache.druid.indexing.common.TaskLock;
 import org.apache.druid.indexing.common.TaskLockType;
@@ -40,7 +38,6 @@ import org.apache.druid.indexing.firehose.IngestSegmentFirehoseFactory;
 import org.apache.druid.indexing.firehose.WindowedSegmentId;
 import org.apache.druid.indexing.overlord.Segments;
 import org.apache.druid.java.util.common.JodaUtils;
-import org.apache.druid.java.util.common.Pair;
 import org.apache.druid.java.util.common.granularity.Granularity;
 import org.apache.druid.java.util.common.granularity.GranularityType;
 import org.apache.druid.java.util.common.logger.Logger;
@@ -48,24 +45,20 @@ import org.apache.druid.segment.indexing.granularity.GranularitySpec;
 import org.apache.druid.timeline.DataSegment;
 import org.apache.druid.timeline.Partitions;
 import org.apache.druid.timeline.VersionedIntervalTimeline;
-import org.apache.druid.timeline.partition.HashBasedNumberedShardSpecFactory;
+import org.apache.druid.timeline.partition.HashBasedNumberedShardSpec;
-import org.apache.druid.timeline.partition.ShardSpecFactory;
 import org.joda.time.Interval;
 import org.joda.time.Period;
 
-import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.GuardedBy;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
-import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.SortedSet;
 import java.util.function.Consumer;
 import java.util.stream.Collectors;
 
@@ -78,24 +71,17 @@ public abstract class AbstractBatchIndexTask extends AbstractTask
 {
   private static final Logger log = new Logger(AbstractBatchIndexTask.class);
 
-  private final SegmentLockHelper segmentLockHelper;
-
   @GuardedBy("this")
   private final TaskResourceCleaner resourceCloserOnAbnormalExit = new TaskResourceCleaner();
 
-  /**
-   * State to indicate that this task will use segmentLock or timeChunkLock.
-   * This is automatically set when {@link #determineLockGranularityandTryLock} is called.
-   */
-  private boolean useSegmentLock;
-
   @GuardedBy("this")
   private boolean stopped = false;
 
+  private TaskLockHelper taskLockHelper;
+
   protected AbstractBatchIndexTask(String id, String dataSource, Map<String, Object> context)
   {
     super(id, dataSource, context);
-    segmentLockHelper = new SegmentLockHelper();
   }
 
   protected AbstractBatchIndexTask(
@@ -107,7 +93,6 @@ public abstract class AbstractBatchIndexTask extends AbstractTask
   )
   {
     super(id, groupId, taskResource, dataSource, context);
-    segmentLockHelper = new SegmentLockHelper();
   }
 
   /**
@@ -194,14 +179,9 @@ public abstract class AbstractBatchIndexTask extends AbstractTask
     return getContextValue(Tasks.PRIORITY_KEY, Tasks.DEFAULT_BATCH_INDEX_TASK_PRIORITY);
   }
 
-  public boolean isUseSegmentLock()
+  public TaskLockHelper getTaskLockHelper()
   {
-    return useSegmentLock;
+    return Preconditions.checkNotNull(taskLockHelper, "taskLockHelper is not initialized yet");
-  }
-
-  public SegmentLockHelper getSegmentLockHelper()
-  {
-    return segmentLockHelper;
   }
 
   /**
@@ -229,7 +209,7 @@ public abstract class AbstractBatchIndexTask extends AbstractTask
     // Respect task context value most.
     if (forceTimeChunkLock) {
       log.info("[%s] is set to true in task context. Use timeChunk lock", Tasks.FORCE_TIME_CHUNK_LOCK_KEY);
-      useSegmentLock = false;
+      taskLockHelper = new TaskLockHelper(false);
       if (!intervals.isEmpty()) {
         return tryTimeChunkLock(client, intervals);
       } else {
@@ -238,7 +218,7 @@ public abstract class AbstractBatchIndexTask extends AbstractTask
     } else {
       if (!intervals.isEmpty()) {
         final LockGranularityDetermineResult result = determineSegmentGranularity(client, intervals);
-        useSegmentLock = result.lockGranularity == LockGranularity.SEGMENT;
+        taskLockHelper = new TaskLockHelper(result.lockGranularity == LockGranularity.SEGMENT);
         return tryLockWithDetermineResult(client, result);
       } else {
         return true;
@@ -255,14 +235,14 @@ public abstract class AbstractBatchIndexTask extends AbstractTask
     );
     if (forceTimeChunkLock) {
       log.info("[%s] is set to true in task context. Use timeChunk lock", Tasks.FORCE_TIME_CHUNK_LOCK_KEY);
-      useSegmentLock = false;
+      taskLockHelper = new TaskLockHelper(false);
       return tryTimeChunkLock(
           client,
           new ArrayList<>(segments.stream().map(DataSegment::getInterval).collect(Collectors.toSet()))
       );
     } else {
       final LockGranularityDetermineResult result = determineSegmentGranularity(segments);
-      useSegmentLock = result.lockGranularity == LockGranularity.SEGMENT;
+      taskLockHelper = new TaskLockHelper(result.lockGranularity == LockGranularity.SEGMENT);
       return tryLockWithDetermineResult(client, result);
     }
   }
@@ -298,7 +278,7 @@ public abstract class AbstractBatchIndexTask extends AbstractTask
     if (result.lockGranularity == LockGranularity.TIME_CHUNK) {
       return tryTimeChunkLock(client, Preconditions.checkNotNull(result.intervals, "intervals"));
     } else {
-      return segmentLockHelper.verifyAndLockExistingSegments(
+      return taskLockHelper.verifyAndLockExistingSegments(
           client,
           Preconditions.checkNotNull(result.segments, "segments")
       );
@@ -377,7 +357,7 @@ public abstract class AbstractBatchIndexTask extends AbstractTask
   /**
    * We currently don't support appending perfectly rolled up segments. This might be supported in the future if there
    * is a good use case. If we want to support appending perfectly rolled up segments, we need to fix some other places
-   * first. For example, {@link org.apache.druid.timeline.partition.HashBasedNumberedShardSpec#getLookup} assumes that
+   * first. For example, {@link HashBasedNumberedShardSpec#getLookup} assumes that
    * the start partition ID of the set of perfectly rolled up segments is 0. Instead it might need to store an ordinal
    * in addition to the partition ID which represents the ordinal in the perfectly rolled up segment set.
    */
@@ -390,14 +370,6 @@ public abstract class AbstractBatchIndexTask extends AbstractTask
     return tuningConfig.isForceGuaranteedRollup();
   }
 
-  static Pair<ShardSpecFactory, Integer> createShardSpecFactoryForGuaranteedRollup(
-      int numShards,
-      @Nullable List<String> partitionDimensions
-  )
-  {
-    return Pair.of(new HashBasedNumberedShardSpecFactory(partitionDimensions, numShards), numShards);
-  }
-
   @Nullable
   static Granularity findGranularityFromSegments(List<DataSegment> segments)
   {
@@ -415,45 +387,6 @@ public abstract class AbstractBatchIndexTask extends AbstractTask
     }
   }
 
-  /**
-   * Creates shard specs based on the given configurations. The return value is a map between intervals created
-   * based on the segment granularity and the shard specs to be created.
-   * Note that the shard specs to be created is a pair of {@link ShardSpecFactory} and number of segments per interval
-   * and filled only when {@link #isGuaranteedRollup} = true. Otherwise, the return value contains only the set of
-   * intervals generated based on the segment granularity.
-   */
-  protected static Map<Interval, Pair<ShardSpecFactory, Integer>> createShardSpecWithoutInputScan(
-      GranularitySpec granularitySpec,
-      IndexIOConfig ioConfig,
-      IndexTuningConfig tuningConfig,
-      @Nonnull PartitionsSpec nonNullPartitionsSpec
-  )
-  {
-    final Map<Interval, Pair<ShardSpecFactory, Integer>> allocateSpec = new HashMap<>();
-    final SortedSet<Interval> intervals = granularitySpec.bucketIntervals().get();
-
-    if (isGuaranteedRollup(ioConfig, tuningConfig)) {
-      // SingleDimensionPartitionsSpec or more partitionsSpec types will be supported in the future.
-      assert nonNullPartitionsSpec instanceof HashedPartitionsSpec;
-      // Overwrite mode, guaranteed rollup: shardSpecs must be known in advance.
-      final HashedPartitionsSpec partitionsSpec = (HashedPartitionsSpec) nonNullPartitionsSpec;
-      final int numShards = partitionsSpec.getNumShards() == null ? 1 : partitionsSpec.getNumShards();
-
-      for (Interval interval : intervals) {
-        allocateSpec.put(
-            interval,
-            createShardSpecFactoryForGuaranteedRollup(numShards, partitionsSpec.getPartitionDimensions())
-        );
-      }
-    } else {
-      for (Interval interval : intervals) {
-        allocateSpec.put(interval, null);
-      }
-    }
-
-    return allocateSpec;
-  }
-
   /**
    * If the given firehoseFactory is {@link IngestSegmentFirehoseFactory}, then it finds the segments to lock
    * from the firehoseFactory. This is because those segments will be read by this task no matter what segments would be

indexing-service/src/main/java/org/apache/druid/indexing/common/task/AppenderatorDriverRealtimeIndexTask.java

@@ -90,7 +90,7 @@ import org.apache.druid.segment.realtime.firehose.TimedShutoffFirehoseFactory;
 import org.apache.druid.segment.realtime.plumber.Committers;
 import org.apache.druid.server.security.Action;
 import org.apache.druid.server.security.AuthorizerMapper;
-import org.apache.druid.timeline.partition.NumberedShardSpecFactory;
+import org.apache.druid.timeline.partition.NumberedPartialShardSpec;
 import org.apache.druid.utils.CircularBuffer;
 
 import javax.servlet.http.HttpServletRequest;
@@ -799,7 +799,7 @@ public class AppenderatorDriverRealtimeIndexTask extends AbstractTask implements
                 sequenceName,
                 previousSegmentId,
                 skipSegmentLineageCheck,
-                NumberedShardSpecFactory.instance(),
+                NumberedPartialShardSpec.instance(),
                 LockGranularity.TIME_CHUNK
             )
         ),

indexing-service/src/main/java/org/apache/druid/indexing/common/task/CachingLocalSegmentAllocator.java

@@ -19,17 +19,21 @@
 
 package org.apache.druid.indexing.common.task;
 
+import com.google.common.base.Preconditions;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.indexing.common.TaskLock;
 import org.apache.druid.indexing.common.TaskToolbox;
 import org.apache.druid.indexing.common.actions.LockListAction;
 import org.apache.druid.indexing.common.actions.SurrogateAction;
+import org.apache.druid.indexing.common.actions.TaskAction;
 import org.apache.druid.indexing.common.task.IndexTask.ShardSpecs;
+import org.apache.druid.indexing.common.task.batch.parallel.SupervisorTaskAccess;
 import org.apache.druid.java.util.common.ISE;
 import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
 import org.apache.druid.timeline.partition.ShardSpec;
 import org.joda.time.Interval;
 
+import javax.annotation.Nullable;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.HashMap;
@@ -41,11 +45,8 @@ import java.util.stream.Collectors;
 
 /**
  * Allocates all necessary segments locally at the beginning and reuses them.
- *
- * @see HashPartitionCachingLocalSegmentAllocator
- * @see RangePartitionCachingLocalSegmentAllocator
  */
-class CachingLocalSegmentAllocatorHelper implements IndexTaskSegmentAllocator
+public class CachingLocalSegmentAllocator implements CachingSegmentAllocator
 {
   private final String taskId;
   private final Map<String, SegmentIdWithShardSpec> sequenceNameToSegmentId;
@@ -59,22 +60,34 @@ class CachingLocalSegmentAllocatorHelper implements IndexTaskSegmentAllocator
      *
      * @return Information for segment preallocation
      */
-    Map<Interval, List<SegmentIdWithShardSpec>> create(Function<Interval, String> versionFinder);
+    Map<Interval, List<SegmentIdWithShardSpec>> create(
+        TaskToolbox toolbox,
+        String dataSource,
+        Function<Interval, String> versionFinder
+    );
   }
 
-  CachingLocalSegmentAllocatorHelper(
+  CachingLocalSegmentAllocator(
       TaskToolbox toolbox,
+      String dataSource,
       String taskId,
-      String supervisorTaskId,
+      @Nullable SupervisorTaskAccess supervisorTaskAccess,
       IntervalToSegmentIdsCreator intervalToSegmentIdsCreator
   ) throws IOException
   {
     this.taskId = taskId;
     this.sequenceNameToSegmentId = new HashMap<>();
 
+    final TaskAction<List<TaskLock>> action;
+    if (supervisorTaskAccess == null) {
+      action = new LockListAction();
+    } else {
+      action = new SurrogateAction<>(supervisorTaskAccess.getSupervisorTaskId(), new LockListAction());
+    }
+
     final Map<Interval, String> intervalToVersion =
         toolbox.getTaskActionClient()
-               .submit(new SurrogateAction<>(supervisorTaskId, new LockListAction()))
+               .submit(action)
                .stream()
                .collect(Collectors.toMap(
                    TaskLock::getInterval,
@@ -82,7 +95,11 @@ class CachingLocalSegmentAllocatorHelper implements IndexTaskSegmentAllocator
                ));
     Function<Interval, String> versionFinder = interval -> findVersion(intervalToVersion, interval);
 
-    final Map<Interval, List<SegmentIdWithShardSpec>> intervalToIds = intervalToSegmentIdsCreator.create(versionFinder);
+    final Map<Interval, List<SegmentIdWithShardSpec>> intervalToIds = intervalToSegmentIdsCreator.create(
+        toolbox,
+        dataSource,
+        versionFinder
+    );
     final Map<Interval, List<ShardSpec>> shardSpecMap = new HashMap<>();
 
     for (Entry<Interval, List<SegmentIdWithShardSpec>> entry : intervalToIds.entrySet()) {
@@ -115,14 +132,11 @@ class CachingLocalSegmentAllocatorHelper implements IndexTaskSegmentAllocator
       boolean skipSegmentLineageCheck
   )
   {
-    return sequenceNameToSegmentId.get(sequenceName);
+    return Preconditions.checkNotNull(
-  }
+        sequenceNameToSegmentId.get(sequenceName),
-
+        "Missing segmentId for the sequence[%s]",
-  @Override
+        sequenceName
-  public String getSequenceName(Interval interval, InputRow inputRow)
+    );
-  {
-    // Sequence name is based solely on the shardSpec, and there will only be one segment per sequence.
-    return getSequenceName(interval, shardSpecs.getShardSpec(interval, inputRow));
   }
 
   /**
@@ -136,4 +150,10 @@ class CachingLocalSegmentAllocatorHelper implements IndexTaskSegmentAllocator
     // and it's faster to add strings together than it is to use String#format
     return taskId + "_" + interval + "_" + shardSpec.getPartitionNum();
   }
+
+  @Override
+  public ShardSpecs getShardSpecs()
+  {
+    return shardSpecs;
+  }
 }

indexing-service/src/main/java/org/apache/druid/indexing/common/task/CachingSegmentAllocator.java

@@ -0,0 +1,39 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.common.task;
+
+import org.apache.druid.indexing.common.task.IndexTask.ShardSpecs;
+import org.apache.druid.segment.realtime.appenderator.SegmentAllocator;
+
+/**
+ * SegmentAllocator that allocates all necessary segments upfront. This allocator should be used for the hash or range
+ * secondary partitioning.
+ *
+ * In the hash or range secondary partitioning, the information about all partition buckets should be known before
+ * the task starts to allocate segments. For example, for the hash partitioning, the task should know how many hash
+ * buckets it will create, what is the hash value allocated for each bucket, etc. Similar for the range partitioning.
+ */
+public interface CachingSegmentAllocator extends SegmentAllocator
+{
+  /**
+   * Returns the {@link org.apache.druid.timeline.partition.ShardSpec}s of all segments allocated upfront.
+   */
+  ShardSpecs getShardSpecs();
+}

indexing-service/src/main/java/org/apache/druid/indexing/common/task/HashPartitionCachingLocalSegmentAllocator.java

@@ -1,116 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *   http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-package org.apache.druid.indexing.common.task;
-
-import com.google.common.base.Preconditions;
-import com.google.common.collect.Maps;
-import org.apache.druid.data.input.InputRow;
-import org.apache.druid.indexing.common.TaskToolbox;
-import org.apache.druid.java.util.common.Pair;
-import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
-import org.apache.druid.timeline.partition.ShardSpecFactory;
-import org.joda.time.Interval;
-
-import java.io.IOException;
-import java.util.List;
-import java.util.Map;
-import java.util.Map.Entry;
-import java.util.function.Function;
-import java.util.stream.Collectors;
-import java.util.stream.IntStream;
-
-/**
- * Allocates all necessary hash-partitioned segments locally at the beginning and reuses them.
- *
- * @see CachingLocalSegmentAllocatorHelper
- */
-public class HashPartitionCachingLocalSegmentAllocator implements IndexTaskSegmentAllocator
-{
-  private final TaskToolbox toolbox;
-  private final String dataSource;
-  private final Map<Interval, Pair<ShardSpecFactory, Integer>> allocateSpec;
-  private final IndexTaskSegmentAllocator delegate;
-
-  public HashPartitionCachingLocalSegmentAllocator(
-      TaskToolbox toolbox,
-      String taskId,
-      String supervisorTaskId,
-      String dataSource,
-      Map<Interval, Pair<ShardSpecFactory, Integer>> allocateSpec
-  ) throws IOException
-  {
-    this.toolbox = toolbox;
-    this.dataSource = dataSource;
-    this.allocateSpec = allocateSpec;
-
-    this.delegate = new CachingLocalSegmentAllocatorHelper(
-        toolbox,
-        taskId,
-        supervisorTaskId,
-        this::getIntervalToSegmentIds
-    );
-  }
-
-  private Map<Interval, List<SegmentIdWithShardSpec>> getIntervalToSegmentIds(Function<Interval, String> versionFinder)
-  {
-    final Map<Interval, List<SegmentIdWithShardSpec>> intervalToSegmentIds =
-        Maps.newHashMapWithExpectedSize(allocateSpec.size());
-
-    for (Entry<Interval, Pair<ShardSpecFactory, Integer>> entry : allocateSpec.entrySet()) {
-      final Interval interval = entry.getKey();
-      final ShardSpecFactory shardSpecFactory = entry.getValue().lhs;
-      final int numSegmentsToAllocate = Preconditions.checkNotNull(
-          entry.getValue().rhs,
-          "numSegmentsToAllocate for interval[%s]",
-          interval
-      );
-
-      intervalToSegmentIds.put(
-          interval,
-          IntStream.range(0, numSegmentsToAllocate)
-                   .mapToObj(i -> new SegmentIdWithShardSpec(
-                       dataSource,
-                       interval,
-                       versionFinder.apply(interval),
-                       shardSpecFactory.create(toolbox.getJsonMapper(), i)
-                   ))
-                   .collect(Collectors.toList())
-      );
-    }
-    return intervalToSegmentIds;
-  }
-
-  @Override
-  public String getSequenceName(Interval interval, InputRow inputRow)
-  {
-    return delegate.getSequenceName(interval, inputRow);
-  }
-
-  @Override
-  public SegmentIdWithShardSpec allocate(
-      InputRow row,
-      String sequenceName,
-      String previousSegmentId,
-      boolean skipSegmentLineageCheck
-  ) throws IOException
-  {
-    return delegate.allocate(row, sequenceName, previousSegmentId, skipSegmentLineageCheck);
-  }
-}

indexing-service/src/main/java/org/apache/druid/indexing/common/task/IndexTask.java

@@ -53,9 +53,9 @@ import org.apache.druid.indexer.TaskStatus;
 import org.apache.druid.indexer.partitions.DynamicPartitionsSpec;
 import org.apache.druid.indexer.partitions.HashedPartitionsSpec;
 import org.apache.druid.indexer.partitions.PartitionsSpec;
+import org.apache.druid.indexer.partitions.SecondaryPartitionType;
 import org.apache.druid.indexing.common.IngestionStatsAndErrorsTaskReport;
 import org.apache.druid.indexing.common.IngestionStatsAndErrorsTaskReportData;
-import org.apache.druid.indexing.common.LockGranularity;
 import org.apache.druid.indexing.common.TaskRealtimeMetricsMonitorBuilder;
 import org.apache.druid.indexing.common.TaskReport;
 import org.apache.druid.indexing.common.TaskToolbox;
@@ -64,14 +64,19 @@ import org.apache.druid.indexing.common.actions.TaskActionClient;
 import org.apache.druid.indexing.common.stats.RowIngestionMeters;
 import org.apache.druid.indexing.common.stats.RowIngestionMetersFactory;
 import org.apache.druid.indexing.common.stats.TaskRealtimeMetricsMonitor;
+import org.apache.druid.indexing.common.task.batch.parallel.PartialHashSegmentGenerateTask;
 import org.apache.druid.indexing.common.task.batch.parallel.iterator.DefaultIndexTaskInputRowIteratorBuilder;
+import org.apache.druid.indexing.common.task.batch.partition.CompletePartitionAnalysis;
+import org.apache.druid.indexing.common.task.batch.partition.HashPartitionAnalysis;
+import org.apache.druid.indexing.common.task.batch.partition.LinearPartitionAnalysis;
+import org.apache.druid.indexing.common.task.batch.partition.PartitionAnalysis;
 import org.apache.druid.indexing.overlord.sampler.InputSourceSampler;
 import org.apache.druid.java.util.common.IAE;
 import org.apache.druid.java.util.common.ISE;
 import org.apache.druid.java.util.common.Intervals;
 import org.apache.druid.java.util.common.JodaUtils;
-import org.apache.druid.java.util.common.Pair;
 import org.apache.druid.java.util.common.StringUtils;
+import org.apache.druid.java.util.common.UOE;
 import org.apache.druid.java.util.common.granularity.Granularity;
 import org.apache.druid.java.util.common.guava.Comparators;
 import org.apache.druid.java.util.common.logger.Logger;
@@ -94,6 +99,7 @@ import org.apache.druid.segment.realtime.appenderator.AppenderatorConfig;
 import org.apache.druid.segment.realtime.appenderator.AppenderatorsManager;
 import org.apache.druid.segment.realtime.appenderator.BaseAppenderatorDriver;
 import org.apache.druid.segment.realtime.appenderator.BatchAppenderatorDriver;
+import org.apache.druid.segment.realtime.appenderator.SegmentAllocator;
 import org.apache.druid.segment.realtime.appenderator.SegmentsAndCommitMetadata;
 import org.apache.druid.segment.realtime.appenderator.TransactionalSegmentPublisher;
 import org.apache.druid.segment.realtime.firehose.ChatHandler;
@@ -105,12 +111,12 @@ import org.apache.druid.timeline.DataSegment;
 import org.apache.druid.timeline.partition.HashBasedNumberedShardSpec;
 import org.apache.druid.timeline.partition.NumberedShardSpec;
 import org.apache.druid.timeline.partition.ShardSpec;
-import org.apache.druid.timeline.partition.ShardSpecFactory;
 import org.apache.druid.utils.CircularBuffer;
 import org.codehaus.plexus.util.FileUtils;
 import org.joda.time.Interval;
 import org.joda.time.Period;
 
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import javax.servlet.http.HttpServletRequest;
 import javax.ws.rs.GET;
@@ -130,6 +136,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
+import java.util.SortedSet;
 import java.util.TreeMap;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
@@ -264,6 +271,13 @@ public class IndexTask extends AbstractBatchIndexTask implements ChatHandler
   @Override
   public boolean isReady(TaskActionClient taskActionClient) throws Exception
   {
+    final IndexTuningConfig tuningConfig = getIngestionSchema().getTuningConfig();
+    if (tuningConfig != null && tuningConfig.getPartitionsSpec() != null) {
+      if (tuningConfig.getPartitionsSpec().getType() != SecondaryPartitionType.LINEAR
+          && tuningConfig.getPartitionsSpec().getType() != SecondaryPartitionType.HASH) {
+        throw new UOE("partitionsSpec[%s] is not supported", tuningConfig.getPartitionsSpec().getClass().getName());
+      }
+    }
     return determineLockGranularityAndTryLock(taskActionClient, ingestionSchema.dataSchema.getGranularitySpec());
   }
 
@@ -487,13 +501,13 @@ public class IndexTask extends AbstractBatchIndexTask implements ChatHandler
       // Initialize maxRowsPerSegment and maxTotalRows lazily
       final IndexTuningConfig tuningConfig = ingestionSchema.tuningConfig;
       final PartitionsSpec partitionsSpec = tuningConfig.getGivenOrDefaultPartitionsSpec();
-      final Map<Interval, Pair<ShardSpecFactory, Integer>> allocateSpec = determineShardSpecs(
+      final PartitionAnalysis partitionAnalysis = determineShardSpecs(
           toolbox,
           inputSource,
           tmpDir,
           partitionsSpec
       );
-      final List<Interval> allocateIntervals = new ArrayList<>(allocateSpec.keySet());
+      final List<Interval> allocateIntervals = new ArrayList<>(partitionAnalysis.getAllIntervalsToIndex());
       final DataSchema dataSchema;
       if (determineIntervals) {
         if (!determineLockGranularityandTryLock(toolbox.getTaskActionClient(), allocateIntervals)) {
@@ -508,14 +522,14 @@ public class IndexTask extends AbstractBatchIndexTask implements ChatHandler
       } else {
         dataSchema = ingestionSchema.getDataSchema();
       }
+
       ingestionState = IngestionState.BUILD_SEGMENTS;
       return generateAndPublishSegments(
           toolbox,
           dataSchema,
-          allocateSpec,
           inputSource,
           tmpDir,
-          partitionsSpec
+          partitionAnalysis
       );
     }
     catch (Exception e) {
@@ -598,16 +612,14 @@ public class IndexTask extends AbstractBatchIndexTask implements ChatHandler
    *
    * @return a map indicating how many shardSpecs need to be created per interval.
    */
-  private Map<Interval, Pair<ShardSpecFactory, Integer>> determineShardSpecs(
+  private PartitionAnalysis determineShardSpecs(
       final TaskToolbox toolbox,
       final InputSource inputSource,
       final File tmpDir,
-      final PartitionsSpec nonNullPartitionsSpec
+      @Nonnull final PartitionsSpec partitionsSpec
   ) throws IOException
   {
     final ObjectMapper jsonMapper = toolbox.getJsonMapper();
-    final IndexTuningConfig tuningConfig = ingestionSchema.getTuningConfig();
-    final IndexIOConfig ioConfig = ingestionSchema.getIOConfig();
 
     final GranularitySpec granularitySpec = ingestionSchema.getDataSchema().getGranularitySpec();
 
@@ -615,42 +627,59 @@ public class IndexTask extends AbstractBatchIndexTask implements ChatHandler
     final boolean determineIntervals = !granularitySpec.bucketIntervals().isPresent();
 
     // Must determine partitions if rollup is guaranteed and the user didn't provide a specific value.
-    final boolean determineNumPartitions = nonNullPartitionsSpec.needsDeterminePartitions(false);
+    final boolean determineNumPartitions = partitionsSpec.needsDeterminePartitions(false);
 
     // if we were given number of shards per interval and the intervals, we don't need to scan the data
     if (!determineNumPartitions && !determineIntervals) {
       log.info("Skipping determine partition scan");
-      return createShardSpecWithoutInputScan(
+      if (partitionsSpec.getType() == SecondaryPartitionType.HASH) {
+        return PartialHashSegmentGenerateTask.createHashPartitionAnalysisFromPartitionsSpec(
             granularitySpec,
-          ioConfig,
+            (HashedPartitionsSpec) partitionsSpec
-          tuningConfig,
-          nonNullPartitionsSpec
         );
+      } else if (partitionsSpec.getType() == SecondaryPartitionType.LINEAR) {
+        return createLinearPartitionAnalysis(granularitySpec, (DynamicPartitionsSpec) partitionsSpec);
+      } else {
+        throw new UOE("%s", partitionsSpec.getClass().getName());
+      }
     } else {
       // determine intervals containing data and prime HLL collectors
+      log.info("Determining intervals and shardSpecs");
       return createShardSpecsFromInput(
           jsonMapper,
           ingestionSchema,
           inputSource,
           tmpDir,
           granularitySpec,
-          nonNullPartitionsSpec,
+          partitionsSpec,
           determineIntervals
       );
     }
   }
 
-  private Map<Interval, Pair<ShardSpecFactory, Integer>> createShardSpecsFromInput(
+  private static LinearPartitionAnalysis createLinearPartitionAnalysis(
+      GranularitySpec granularitySpec,
+      @Nonnull DynamicPartitionsSpec partitionsSpec
+  )
+  {
+    final SortedSet<Interval> intervals = granularitySpec.bucketIntervals().get();
+    final int numBucketsPerInterval = 1;
+    final LinearPartitionAnalysis partitionAnalysis = new LinearPartitionAnalysis(partitionsSpec);
+    intervals.forEach(interval -> partitionAnalysis.updateBucket(interval, numBucketsPerInterval));
+    return partitionAnalysis;
+  }
+
+  private PartitionAnalysis createShardSpecsFromInput(
       ObjectMapper jsonMapper,
       IndexIngestionSpec ingestionSchema,
       InputSource inputSource,
       File tmpDir,
       GranularitySpec granularitySpec,
-      PartitionsSpec nonNullPartitionsSpec,
+      @Nonnull PartitionsSpec partitionsSpec,
       boolean determineIntervals
   ) throws IOException
   {
-    log.info("Determining intervals and shardSpecs");
+    assert partitionsSpec.getType() != SecondaryPartitionType.RANGE;
     long determineShardSpecsStartMillis = System.currentTimeMillis();
 
     final Map<Interval, Optional<HyperLogLogCollector>> hllCollectors = collectIntervalsAndShardSpecs(
@@ -659,50 +688,49 @@ public class IndexTask extends AbstractBatchIndexTask implements ChatHandler
         inputSource,
         tmpDir,
         granularitySpec,
-        nonNullPartitionsSpec,
+        partitionsSpec,
         determineIntervals
     );
-
+    final PartitionAnalysis<Integer, ?> partitionAnalysis;
-    final Map<Interval, Pair<ShardSpecFactory, Integer>> allocateSpecs = new HashMap<>();
+    if (partitionsSpec.getType() == SecondaryPartitionType.LINEAR) {
+      partitionAnalysis = new LinearPartitionAnalysis((DynamicPartitionsSpec) partitionsSpec);
+    } else if (partitionsSpec.getType() == SecondaryPartitionType.HASH) {
+      partitionAnalysis = new HashPartitionAnalysis((HashedPartitionsSpec) partitionsSpec);
+    } else {
+      throw new UOE("%s", partitionsSpec.getClass().getName());
+    }
     for (final Map.Entry<Interval, Optional<HyperLogLogCollector>> entry : hllCollectors.entrySet()) {
       final Interval interval = entry.getKey();
-
+      final int numBucketsPerInterval;
-      if (isGuaranteedRollup(ingestionSchema.getIOConfig(), ingestionSchema.getTuningConfig())) {
+      if (partitionsSpec.getType() == SecondaryPartitionType.HASH) {
-        assert nonNullPartitionsSpec instanceof HashedPartitionsSpec;
+        final HashedPartitionsSpec hashedPartitionsSpec = (HashedPartitionsSpec) partitionsSpec;
-        final HashedPartitionsSpec partitionsSpec = (HashedPartitionsSpec) nonNullPartitionsSpec;
-
         final HyperLogLogCollector collector = entry.getValue().orNull();
 
-        final int numShards;
         if (partitionsSpec.needsDeterminePartitions(false)) {
           final long numRows = Preconditions.checkNotNull(collector, "HLL collector").estimateCardinalityRound();
           final int nonNullMaxRowsPerSegment = partitionsSpec.getMaxRowsPerSegment() == null
                                                ? PartitionsSpec.DEFAULT_MAX_ROWS_PER_SEGMENT
                                                : partitionsSpec.getMaxRowsPerSegment();
-          numShards = (int) Math.ceil((double) numRows / nonNullMaxRowsPerSegment);
+          numBucketsPerInterval = (int) Math.ceil((double) numRows / nonNullMaxRowsPerSegment);
           log.info(
               "Estimated [%,d] rows of data for interval [%s], creating [%,d] shards",
               numRows,
               interval,
-              numShards
+              numBucketsPerInterval
           );
         } else {
-          numShards = partitionsSpec.getNumShards() == null ? 1 : partitionsSpec.getNumShards();
+          numBucketsPerInterval = hashedPartitionsSpec.getNumShards() == null ? 1 : hashedPartitionsSpec.getNumShards();
-          log.info("Creating [%,d] shards for interval [%s]", numShards, interval);
+          log.info("Creating [%,d] buckets for interval [%s]", numBucketsPerInterval, interval);
+        }
+      } else {
+        numBucketsPerInterval = 1;
       }
 
-        // Overwrite mode, guaranteed rollup: shardSpecs must be known in advance.
+      partitionAnalysis.updateBucket(interval, numBucketsPerInterval);
-        allocateSpecs.put(
-            interval,
-            createShardSpecFactoryForGuaranteedRollup(numShards, partitionsSpec.getPartitionDimensions())
-        );
-      } else {
-        allocateSpecs.put(interval, null);
-      }
     }
     log.info("Found intervals and shardSpecs in %,dms", System.currentTimeMillis() - determineShardSpecsStartMillis);
 
-    return allocateSpecs;
+    return partitionAnalysis;
   }
 
   private Map<Interval, Optional<HyperLogLogCollector>> collectIntervalsAndShardSpecs(
@@ -711,7 +739,7 @@ public class IndexTask extends AbstractBatchIndexTask implements ChatHandler
       InputSource inputSource,
       File tmpDir,
       GranularitySpec granularitySpec,
-      PartitionsSpec nonNullPartitionsSpec,
+      @Nonnull PartitionsSpec partitionsSpec,
       boolean determineIntervals
   ) throws IOException
   {
@@ -765,7 +793,7 @@ public class IndexTask extends AbstractBatchIndexTask implements ChatHandler
             interval = optInterval.get();
           }
 
-          if (nonNullPartitionsSpec.needsDeterminePartitions(false)) {
+          if (partitionsSpec.needsDeterminePartitions(false)) {
             hllCollectors.computeIfAbsent(interval, intv -> Optional.of(HyperLogLogCollector.makeLatestCollector()));
 
             List<Object> groupKey = Rows.toGroupKey(
@@ -809,32 +837,6 @@ public class IndexTask extends AbstractBatchIndexTask implements ChatHandler
     return hllCollectors;
   }
 
-  private IndexTaskSegmentAllocator createSegmentAllocator(
-      TaskToolbox toolbox,
-      DataSchema dataSchema,
-      Map<Interval, Pair<ShardSpecFactory, Integer>> allocateSpec
-  ) throws IOException
-  {
-    if (ingestionSchema.ioConfig.isAppendToExisting() || isUseSegmentLock()) {
-      return new RemoteSegmentAllocator(
-          toolbox,
-          getId(),
-          dataSchema,
-          getSegmentLockHelper(),
-          isUseSegmentLock() ? LockGranularity.SEGMENT : LockGranularity.TIME_CHUNK,
-          ingestionSchema.ioConfig.isAppendToExisting()
-      );
-    } else {
-      // We use the timeChunk lock and don't have to ask the overlord to create segmentIds.
-      // Instead, a local allocator is used.
-      if (isGuaranteedRollup(ingestionSchema.ioConfig, ingestionSchema.tuningConfig)) {
-        return new HashPartitionCachingLocalSegmentAllocator(toolbox, getId(), getId(), getDataSource(), allocateSpec);
-      } else {
-        return new LocalSegmentAllocator(toolbox, getId(), getDataSource(), dataSchema.getGranularitySpec());
-      }
-    }
-  }
-
   /**
    * This method reads input data row by row and adds the read row to a proper segment using {@link BaseAppenderatorDriver}.
    * If there is no segment for the row, a new one is created.  Segments can be published in the middle of reading inputs
@@ -856,10 +858,9 @@ public class IndexTask extends AbstractBatchIndexTask implements ChatHandler
   private TaskStatus generateAndPublishSegments(
       final TaskToolbox toolbox,
       final DataSchema dataSchema,
-      final Map<Interval, Pair<ShardSpecFactory, Integer>> allocateSpec,
       final InputSource inputSource,
       final File tmpDir,
-      final PartitionsSpec partitionsSpec
+      final PartitionAnalysis partitionAnalysis
   ) throws IOException, InterruptedException
   {
     final FireDepartment fireDepartmentForMetrics =
@@ -875,14 +876,42 @@ public class IndexTask extends AbstractBatchIndexTask implements ChatHandler
       toolbox.getMonitorScheduler().addMonitor(metricsMonitor);
     }
 
+    final PartitionsSpec partitionsSpec = partitionAnalysis.getPartitionsSpec();
     final IndexTuningConfig tuningConfig = ingestionSchema.getTuningConfig();
     final long pushTimeout = tuningConfig.getPushTimeout();
 
-    final IndexTaskSegmentAllocator segmentAllocator = createSegmentAllocator(
+    final SegmentAllocator segmentAllocator;
+    final SequenceNameFunction sequenceNameFunction;
+    switch (partitionsSpec.getType()) {
+      case HASH:
+      case RANGE:
+        final CachingSegmentAllocator localSegmentAllocator = SegmentAllocators.forNonLinearPartitioning(
             toolbox,
-        dataSchema,
+            getDataSource(),
-        allocateSpec
+            getId(),
+            null,
+            (CompletePartitionAnalysis) partitionAnalysis
         );
+        sequenceNameFunction = new NonLinearlyPartitionedSequenceNameFunction(
+            getId(),
+            localSegmentAllocator.getShardSpecs()
+        );
+        segmentAllocator = localSegmentAllocator;
+        break;
+      case LINEAR:
+        segmentAllocator = SegmentAllocators.forLinearPartitioning(
+            toolbox,
+            null,
+            dataSchema,
+            getTaskLockHelper(),
+            ingestionSchema.getIOConfig().isAppendToExisting(),
+            partitionAnalysis.getPartitionsSpec()
+        );
+        sequenceNameFunction = new LinearlyPartitionedSequenceNameFunction(getId());
+        break;
+      default:
+        throw new UOE("[%s] secondary partition type is not supported", partitionsSpec.getType());
+    }
 
     final TransactionalSegmentPublisher publisher = (segmentsToBeOverwritten, segmentsToPublish, commitMetadata) ->
         toolbox.getTaskActionClient()
@@ -921,13 +950,13 @@ public class IndexTask extends AbstractBatchIndexTask implements ChatHandler
           inputSource,
           inputSource.needsFormat() ? getInputFormat(ingestionSchema) : null,
           tmpDir,
-          segmentAllocator
+          sequenceNameFunction
       );
 
       // If we use timeChunk lock, then we don't have to specify what segments will be overwritten because
       // it will just overwrite all segments overlapped with the new segments.
-      final Set<DataSegment> inputSegments = isUseSegmentLock()
+      final Set<DataSegment> inputSegments = getTaskLockHelper().isUseSegmentLock()
-                                             ? getSegmentLockHelper().getLockedExistingSegments()
+                                             ? getTaskLockHelper().getLockedExistingSegments()
                                              : null;
       // Probably we can publish atomicUpdateGroup along with segments.
       final SegmentsAndCommitMetadata published =
@@ -1207,11 +1236,6 @@ public class IndexTask extends AbstractBatchIndexTask implements ChatHandler
     @Nullable
     private final SegmentWriteOutMediumFactory segmentWriteOutMediumFactory;
 
-    static IndexTuningConfig createDefault()
-    {
-      return new IndexTuningConfig();
-    }
-
     @Nullable
     private static PartitionsSpec getDefaultPartitionsSpec(
         boolean forceGuaranteedRollup,

indexing-service/src/main/java/org/apache/druid/indexing/common/task/InputSourceProcessor.java

@@ -96,7 +96,7 @@ public class InputSourceProcessor
       InputSource inputSource,
       @Nullable InputFormat inputFormat,
       File tmpDir,
-      IndexTaskSegmentAllocator segmentAllocator
+      SequenceNameFunction sequenceNameFunction
   ) throws IOException, InterruptedException, ExecutionException, TimeoutException
   {
     @Nullable
@@ -140,7 +140,7 @@ public class InputSourceProcessor
           @SuppressWarnings("OptionalGetWithoutIsPresent")
           final Interval interval = optInterval.get();
 
-          final String sequenceName = segmentAllocator.getSequenceName(interval, inputRow);
+          final String sequenceName = sequenceNameFunction.getSequenceName(interval, inputRow);
           final AppenderatorDriverAddResult addResult = driver.add(inputRow, sequenceName);
 
           if (addResult.isOk()) {

indexing-service/src/main/java/org/apache/druid/indexing/common/task/LinearlyPartitionedSequenceNameFunction.java

@@ -0,0 +1,45 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.common.task;
+
+import org.apache.druid.data.input.InputRow;
+import org.joda.time.Interval;
+
+/**
+ * This sequence name function should be used for the linear partitioning. Since the segments are created as needed,
+ * this function uses a single sequence name.
+ *
+ * @see org.apache.druid.indexer.partitions.SecondaryPartitionType
+ */
+public class LinearlyPartitionedSequenceNameFunction implements SequenceNameFunction
+{
+  private final String taskId;
+
+  LinearlyPartitionedSequenceNameFunction(String taskId)
+  {
+    this.taskId = taskId;
+  }
+
+  @Override
+  public String getSequenceName(Interval interval, InputRow inputRow)
+  {
+    return taskId;
+  }
+}

indexing-service/src/main/java/org/apache/druid/indexing/common/task/LocalSegmentAllocator.java

@@ -20,6 +20,8 @@
 package org.apache.druid.indexing.common.task;
 
 import com.google.common.base.Optional;
+import com.google.common.collect.Maps;
+import org.apache.commons.lang3.mutable.MutableInt;
 import org.apache.druid.data.input.InputRow;
 import org.apache.druid.indexing.common.TaskLock;
 import org.apache.druid.indexing.common.TaskToolbox;
@@ -32,32 +34,27 @@ import org.apache.druid.timeline.partition.NumberedShardSpec;
 import org.joda.time.DateTime;
 import org.joda.time.Interval;
 
+import javax.annotation.Nullable;
 import java.io.IOException;
-import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
-import java.util.concurrent.atomic.AtomicInteger;
 import java.util.stream.Collectors;
 
 /**
  * Segment allocator which allocates new segments locally per request.
  */
-class LocalSegmentAllocator implements IndexTaskSegmentAllocator
+class LocalSegmentAllocator implements SegmentAllocator
 {
-  private final String taskId;
-
   private final SegmentAllocator internalAllocator;
 
-  LocalSegmentAllocator(TaskToolbox toolbox, String taskId, String dataSource, GranularitySpec granularitySpec)
+  LocalSegmentAllocator(TaskToolbox toolbox, String dataSource, GranularitySpec granularitySpec) throws IOException
-      throws IOException
   {
-    this.taskId = taskId;
+    final Map<Interval, String> intervalToVersion = toolbox
-    final Map<Interval, AtomicInteger> counters = new HashMap<>();
+        .getTaskActionClient()
-
-    final Map<Interval, String> intervalToVersion = toolbox.getTaskActionClient()
         .submit(new LockListAction())
         .stream()
         .collect(Collectors.toMap(TaskLock::getInterval, TaskLock::getVersion));
+    final Map<Interval, MutableInt> counters = Maps.newHashMapWithExpectedSize(intervalToVersion.size());
 
     internalAllocator = (row, sequenceName, previousSegmentId, skipSegmentLineageCheck) -> {
       final DateTime timestamp = row.getTimestamp();
@@ -67,30 +64,25 @@ class LocalSegmentAllocator implements IndexTaskSegmentAllocator
       }
 
       final Interval interval = maybeInterval.get();
-      final String version = intervalToVersion.entrySet().stream()
+      final String version = intervalToVersion
+          .entrySet()
+          .stream()
           .filter(entry -> entry.getKey().contains(interval))
           .map(Entry::getValue)
           .findFirst()
           .orElseThrow(() -> new ISE("Cannot find a version for interval[%s]", interval));
 
-      final int partitionNum = counters.computeIfAbsent(interval, x -> new AtomicInteger()).getAndIncrement();
+      final int partitionId = counters.computeIfAbsent(interval, x -> new MutableInt()).getAndIncrement();
       return new SegmentIdWithShardSpec(
           dataSource,
           interval,
           version,
-          new NumberedShardSpec(partitionNum, 0)
+          new NumberedShardSpec(partitionId, 0)
       );
     };
   }
 
-  @Override
+  @Nullable
-  public String getSequenceName(Interval interval, InputRow inputRow)
-  {
-    // Segments are created as needed, using a single sequence name. They may be allocated from the overlord
-    // (in append mode) or may be created on our own authority (in overwrite mode).
-    return taskId;
-  }
-
   @Override
   public SegmentIdWithShardSpec allocate(
       InputRow row,

indexing-service/src/main/java/org/apache/druid/indexing/common/task/NonLinearlyPartitionedSequenceNameFunction.java

@@ -0,0 +1,65 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.common.task;
+
+import org.apache.druid.data.input.InputRow;
+import org.apache.druid.indexing.common.task.IndexTask.ShardSpecs;
+import org.apache.druid.timeline.partition.ShardSpec;
+import org.joda.time.Interval;
+
+/**
+ * This sequence name function should be used for the hash or range partitioning. This function creates a proper
+ * sequence name based on the partition information (time chunk + partition ID).
+ *
+ * Note that all segment IDs should be allocated upfront to use this function.
+ *
+ * @see org.apache.druid.indexer.partitions.SecondaryPartitionType
+ * @see CachingSegmentAllocator
+ */
+public class NonLinearlyPartitionedSequenceNameFunction implements SequenceNameFunction
+{
+  private final String taskId;
+  private final ShardSpecs shardSpecs;
+
+  public NonLinearlyPartitionedSequenceNameFunction(String taskId, ShardSpecs shardSpecs)
+  {
+    this.taskId = taskId;
+    this.shardSpecs = shardSpecs;
+  }
+
+  @Override
+  public String getSequenceName(Interval interval, InputRow inputRow)
+  {
+    // Sequence name is based solely on the shardSpec, and there will only be one segment per sequence.
+    return getSequenceName(interval, shardSpecs.getShardSpec(interval, inputRow));
+  }
+
+  /**
+   * Create a sequence name from the given shardSpec and interval.
+   *
+   * See {@link org.apache.druid.timeline.partition.HashBasedNumberedShardSpec} as an example of partitioning.
+   */
+  private String getSequenceName(Interval interval, ShardSpec shardSpec)
+  {
+    // Note: We do not use String format here since this can be called in a tight loop
+    // and it's faster to add strings together than it is to use String#format
+    return taskId + "_" + interval + "_" + shardSpec.getPartitionNum();
+  }
+}

indexing-service/src/main/java/org/apache/druid/indexing/common/task/OverlordCoordinatingSegmentAllocator.java

@@ -0,0 +1,149 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.common.task;
+
+import org.apache.druid.data.input.InputRow;
+import org.apache.druid.indexer.partitions.PartitionsSpec;
+import org.apache.druid.indexer.partitions.SecondaryPartitionType;
+import org.apache.druid.indexing.appenderator.ActionBasedSegmentAllocator;
+import org.apache.druid.indexing.common.TaskToolbox;
+import org.apache.druid.indexing.common.actions.SegmentAllocateAction;
+import org.apache.druid.indexing.common.actions.SurrogateAction;
+import org.apache.druid.indexing.common.task.TaskLockHelper.OverwritingRootGenerationPartitions;
+import org.apache.druid.indexing.common.task.batch.parallel.SupervisorTaskAccess;
+import org.apache.druid.java.util.common.ISE;
+import org.apache.druid.segment.indexing.DataSchema;
+import org.apache.druid.segment.indexing.granularity.GranularitySpec;
+import org.apache.druid.segment.realtime.appenderator.SegmentAllocator;
+import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
+import org.apache.druid.timeline.partition.NumberedOverwritePartialShardSpec;
+import org.apache.druid.timeline.partition.NumberedPartialShardSpec;
+import org.apache.druid.timeline.partition.PartialShardSpec;
+import org.joda.time.Interval;
+
+import javax.annotation.Nullable;
+import java.io.IOException;
+
+/**
+ * Segment allocator which allocates new segments using the overlord per request.
+ */
+public class OverlordCoordinatingSegmentAllocator implements SegmentAllocator
+{
+  private final ActionBasedSegmentAllocator internalAllocator;
+
+  OverlordCoordinatingSegmentAllocator(
+      final TaskToolbox toolbox,
+      final @Nullable SupervisorTaskAccess supervisorTaskAccess,
+      final DataSchema dataSchema,
+      final TaskLockHelper taskLockHelper,
+      final boolean appendToExisting,
+      final PartitionsSpec partitionsSpec
+  )
+  {
+    this.internalAllocator = new ActionBasedSegmentAllocator(
+        toolbox.getTaskActionClient(),
+        dataSchema,
+        (schema, row, sequenceName, previousSegmentId, skipSegmentLineageCheck) -> {
+          final GranularitySpec granularitySpec = schema.getGranularitySpec();
+          final Interval interval = granularitySpec
+              .bucketInterval(row.getTimestamp())
+              .or(granularitySpec.getSegmentGranularity().bucket(row.getTimestamp()));
+          final PartialShardSpec partialShardSpec = createPartialShardSpec(
+              appendToExisting,
+              partitionsSpec,
+              taskLockHelper,
+              interval
+          );
+          if (supervisorTaskAccess != null) {
+            return new SurrogateAction<>(
+                supervisorTaskAccess.getSupervisorTaskId(),
+                new SegmentAllocateAction(
+                    schema.getDataSource(),
+                    row.getTimestamp(),
+                    schema.getGranularitySpec().getQueryGranularity(),
+                    schema.getGranularitySpec().getSegmentGranularity(),
+                    sequenceName,
+                    previousSegmentId,
+                    skipSegmentLineageCheck,
+                    partialShardSpec,
+                    taskLockHelper.getLockGranularityToUse()
+                )
+            );
+          } else {
+            return new SegmentAllocateAction(
+                schema.getDataSource(),
+                row.getTimestamp(),
+                schema.getGranularitySpec().getQueryGranularity(),
+                schema.getGranularitySpec().getSegmentGranularity(),
+                sequenceName,
+                previousSegmentId,
+                skipSegmentLineageCheck,
+                partialShardSpec,
+                taskLockHelper.getLockGranularityToUse()
+            );
+          }
+        }
+    );
+  }
+
+  @Nullable
+  @Override
+  public SegmentIdWithShardSpec allocate(
+      InputRow row,
+      String sequenceName,
+      String previousSegmentId,
+      boolean skipSegmentLineageCheck
+  ) throws IOException
+  {
+    return internalAllocator.allocate(row, sequenceName, previousSegmentId, skipSegmentLineageCheck);
+  }
+
+  private static PartialShardSpec createPartialShardSpec(
+      boolean appendToExisting,
+      PartitionsSpec partitionsSpec,
+      TaskLockHelper taskLockHelper,
+      Interval interval
+  )
+  {
+    if (partitionsSpec.getType() == SecondaryPartitionType.LINEAR) {
+      if (taskLockHelper.isUseSegmentLock()) {
+        if (taskLockHelper.hasOverwritingRootGenerationPartition(interval) && !appendToExisting) {
+          final OverwritingRootGenerationPartitions overwritingRootGenerationPartitions = taskLockHelper
+              .getOverwritingRootGenerationPartition(interval);
+          if (overwritingRootGenerationPartitions == null) {
+            throw new ISE("Can't find overwritingSegmentMeta for interval[%s]", interval);
+          }
+          return new NumberedOverwritePartialShardSpec(
+              overwritingRootGenerationPartitions.getStartRootPartitionId(),
+              overwritingRootGenerationPartitions.getEndRootPartitionId(),
+              overwritingRootGenerationPartitions.getMinorVersionForNewSegments()
+          );
+        }
+      }
+      return NumberedPartialShardSpec.instance();
+    } else {
+      throw new ISE(
+          "%s is not supported for partitionsSpec[%s]",
+          OverlordCoordinatingSegmentAllocator.class.getName(),
+          partitionsSpec.getClass().getName()
+      );
+    }
+  }
+}

indexing-service/src/main/java/org/apache/druid/indexing/common/task/RangePartitionCachingLocalSegmentAllocator.java

@@ -1,152 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *   http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-package org.apache.druid.indexing.common.task;
-
-import com.google.common.collect.Maps;
-import org.apache.druid.data.input.InputRow;
-import org.apache.druid.indexing.common.TaskToolbox;
-import org.apache.druid.indexing.common.task.batch.parallel.distribution.PartitionBoundaries;
-import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
-import org.apache.druid.timeline.partition.SingleDimensionShardSpec;
-import org.joda.time.Interval;
-
-import javax.annotation.Nullable;
-import java.io.IOException;
-import java.util.Collections;
-import java.util.List;
-import java.util.Map;
-import java.util.function.Function;
-import java.util.stream.Collectors;
-import java.util.stream.IntStream;
-
-/**
- * Allocates all necessary range-partitioned segments locally at the beginning and reuses them.
- *
- * @see CachingLocalSegmentAllocatorHelper
- */
-public class RangePartitionCachingLocalSegmentAllocator implements IndexTaskSegmentAllocator
-{
-  private final String dataSource;
-  private final String partitionDimension;
-  private final Map<Interval, PartitionBoundaries> intervalsToPartitions;
-  private final IndexTaskSegmentAllocator delegate;
-
-  public RangePartitionCachingLocalSegmentAllocator(
-      TaskToolbox toolbox,
-      String taskId,
-      String supervisorTaskId,
-      String dataSource,
-      String partitionDimension,
-      Map<Interval, PartitionBoundaries> intervalsToPartitions
-  ) throws IOException
-  {
-    this.dataSource = dataSource;
-    this.partitionDimension = partitionDimension;
-    this.intervalsToPartitions = intervalsToPartitions;
-
-    this.delegate = new CachingLocalSegmentAllocatorHelper(
-        toolbox,
-        taskId,
-        supervisorTaskId,
-        this::getIntervalToSegmentIds
-    );
-  }
-
-  private Map<Interval, List<SegmentIdWithShardSpec>> getIntervalToSegmentIds(Function<Interval, String> versionFinder)
-  {
-    Map<Interval, List<SegmentIdWithShardSpec>> intervalToSegmentIds =
-        Maps.newHashMapWithExpectedSize(intervalsToPartitions.size());
-
-    intervalsToPartitions.forEach(
-        (interval, partitionBoundaries) ->
-            intervalToSegmentIds.put(
-                interval,
-                translatePartitionBoundaries(interval, partitionBoundaries, versionFinder)
-            )
-    );
-
-    return intervalToSegmentIds;
-  }
-
-  /**
-   * Translate {@link PartitionBoundaries} into the corresponding
-   * {@link org.apache.druid.indexer.partitions.SingleDimensionPartitionsSpec} with segment id.
-   */
-  private List<SegmentIdWithShardSpec> translatePartitionBoundaries(
-      Interval interval,
-      PartitionBoundaries partitionBoundaries,
-      Function<Interval, String> versionFinder
-  )
-  {
-    if (partitionBoundaries.isEmpty()) {
-      return Collections.emptyList();
-    }
-
-    return IntStream.range(0, partitionBoundaries.size() - 1)
-                    .mapToObj(i -> createSegmentIdWithShardSpec(
-                        interval,
-                        versionFinder.apply(interval),
-                        partitionBoundaries.get(i),
-                        partitionBoundaries.get(i + 1),
-                        i
-                    ))
-                    .collect(Collectors.toList());
-  }
-
-  private SegmentIdWithShardSpec createSegmentIdWithShardSpec(
-      Interval interval,
-      String version,
-      String partitionStart,
-      @Nullable String partitionEnd,
-      int partitionNum
-  )
-  {
-    // The shardSpec created here will be reused in PartialGenericSegmentMergeTask. This is ok because
-    // all PartialSegmentGenerateTasks create the same set of segmentIds (and thus shardSpecs).
-    return new SegmentIdWithShardSpec(
-        dataSource,
-        interval,
-        version,
-        new SingleDimensionShardSpec(
-            partitionDimension,
-            partitionStart,
-            partitionEnd,
-            partitionNum
-        )
-    );
-  }
-
-  @Override
-  public String getSequenceName(Interval interval, InputRow inputRow)
-  {
-    return delegate.getSequenceName(interval, inputRow);
-  }
-
-  @Override
-  public SegmentIdWithShardSpec allocate(
-      InputRow row,
-      String sequenceName,
-      String previousSegmentId,
-      boolean skipSegmentLineageCheck
-  ) throws IOException
-  {
-    return delegate.allocate(row, sequenceName, previousSegmentId, skipSegmentLineageCheck);
-  }
-}

indexing-service/src/main/java/org/apache/druid/indexing/common/task/RemoteSegmentAllocator.java

@@ -1,127 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *   http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-package org.apache.druid.indexing.common.task;
-
-import org.apache.druid.data.input.InputRow;
-import org.apache.druid.indexing.appenderator.ActionBasedSegmentAllocator;
-import org.apache.druid.indexing.common.LockGranularity;
-import org.apache.druid.indexing.common.TaskToolbox;
-import org.apache.druid.indexing.common.actions.SegmentAllocateAction;
-import org.apache.druid.indexing.common.task.SegmentLockHelper.OverwritingRootGenerationPartitions;
-import org.apache.druid.java.util.common.ISE;
-import org.apache.druid.segment.indexing.DataSchema;
-import org.apache.druid.segment.indexing.granularity.GranularitySpec;
-import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
-import org.apache.druid.timeline.partition.NumberedOverwritingShardSpecFactory;
-import org.apache.druid.timeline.partition.NumberedShardSpecFactory;
-import org.apache.druid.timeline.partition.ShardSpecFactory;
-import org.joda.time.Interval;
-
-import java.io.IOException;
-
-/**
- * Segment allocator which allocates new segments using the overlord per request.
- */
-public class RemoteSegmentAllocator implements IndexTaskSegmentAllocator
-{
-  private final String taskId;
-  private final ActionBasedSegmentAllocator internalAllocator;
-
-  RemoteSegmentAllocator(
-      final TaskToolbox toolbox,
-      final String taskId,
-      final DataSchema dataSchema,
-      final SegmentLockHelper segmentLockHelper,
-      final LockGranularity lockGranularity,
-      final boolean appendToExisting
-  )
-  {
-    this.taskId = taskId;
-    this.internalAllocator = new ActionBasedSegmentAllocator(
-        toolbox.getTaskActionClient(),
-        dataSchema,
-        (schema, row, sequenceName, previousSegmentId, skipSegmentLineageCheck) -> {
-          final GranularitySpec granularitySpec = schema.getGranularitySpec();
-          final Interval interval = granularitySpec
-              .bucketInterval(row.getTimestamp())
-              .or(granularitySpec.getSegmentGranularity().bucket(row.getTimestamp()));
-          if (lockGranularity == LockGranularity.TIME_CHUNK) {
-            return new SegmentAllocateAction(
-                schema.getDataSource(),
-                row.getTimestamp(),
-                schema.getGranularitySpec().getQueryGranularity(),
-                schema.getGranularitySpec().getSegmentGranularity(),
-                sequenceName,
-                previousSegmentId,
-                skipSegmentLineageCheck,
-                NumberedShardSpecFactory.instance(),
-                lockGranularity
-            );
-          } else {
-            final ShardSpecFactory shardSpecFactory;
-            if (segmentLockHelper.hasLockedExistingSegments() && !appendToExisting) {
-              final OverwritingRootGenerationPartitions overwritingSegmentMeta = segmentLockHelper
-                  .getOverwritingRootGenerationPartition(interval);
-              if (overwritingSegmentMeta == null) {
-                throw new ISE("Can't find overwritingSegmentMeta for interval[%s]", interval);
-              }
-              shardSpecFactory = new NumberedOverwritingShardSpecFactory(
-                  overwritingSegmentMeta.getStartRootPartitionId(),
-                  overwritingSegmentMeta.getEndRootPartitionId(),
-                  overwritingSegmentMeta.getMinorVersionForNewSegments()
-              );
-            } else {
-              shardSpecFactory = NumberedShardSpecFactory.instance();
-            }
-            return new SegmentAllocateAction(
-                schema.getDataSource(),
-                row.getTimestamp(),
-                schema.getGranularitySpec().getQueryGranularity(),
-                schema.getGranularitySpec().getSegmentGranularity(),
-                sequenceName,
-                previousSegmentId,
-                skipSegmentLineageCheck,
-                shardSpecFactory,
-                lockGranularity
-            );
-          }
-        }
-    );
-  }
-
-  @Override
-  public SegmentIdWithShardSpec allocate(
-      InputRow row,
-      String sequenceName,
-      String previousSegmentId,
-      boolean skipSegmentLineageCheck
-  ) throws IOException
-  {
-    return internalAllocator.allocate(row, sequenceName, previousSegmentId, skipSegmentLineageCheck);
-  }
-
-  @Override
-  public String getSequenceName(Interval interval, InputRow inputRow)
-  {
-    // Segments are created as needed, using a single sequence name. They may be allocated from the overlord
-    // (in append mode) or may be created on our own authority (in overwrite mode).
-    return taskId;
-  }
-}

indexing-service/src/main/java/org/apache/druid/indexing/common/task/SegmentAllocators.java

@@ -0,0 +1,96 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.common.task;
+
+import org.apache.druid.indexer.partitions.PartitionsSpec;
+import org.apache.druid.indexing.common.TaskToolbox;
+import org.apache.druid.indexing.common.task.batch.parallel.SupervisorTaskAccess;
+import org.apache.druid.indexing.common.task.batch.partition.CompletePartitionAnalysis;
+import org.apache.druid.segment.indexing.DataSchema;
+import org.apache.druid.segment.realtime.appenderator.SegmentAllocator;
+
+import javax.annotation.Nullable;
+import java.io.IOException;
+
+public final class SegmentAllocators
+{
+  /**
+   * Creates a new {@link SegmentAllocator} for the linear partitioning.
+   * supervisorTaskAccess can be null if this method is called by the {@link IndexTask}.
+   */
+  public static SegmentAllocator forLinearPartitioning(
+      final TaskToolbox toolbox,
+      final @Nullable SupervisorTaskAccess supervisorTaskAccess,
+      final DataSchema dataSchema,
+      final TaskLockHelper taskLockHelper,
+      final boolean appendToExisting,
+      final PartitionsSpec partitionsSpec
+  ) throws IOException
+  {
+    if (appendToExisting || taskLockHelper.isUseSegmentLock()) {
+      return new OverlordCoordinatingSegmentAllocator(
+          toolbox,
+          supervisorTaskAccess,
+          dataSchema,
+          taskLockHelper,
+          appendToExisting,
+          partitionsSpec
+      );
+    } else {
+      if (supervisorTaskAccess == null) {
+        return new LocalSegmentAllocator(
+            toolbox,
+            dataSchema.getDataSource(),
+            dataSchema.getGranularitySpec()
+        );
+      } else {
+        return new SupervisorTaskCoordinatingSegmentAllocator(
+            supervisorTaskAccess.getSupervisorTaskId(),
+            supervisorTaskAccess.getTaskClient()
+        );
+      }
+    }
+  }
+
+  /**
+   * Creates a new {@link SegmentAllocator} for the hash and range partitioning.
+   * supervisorTaskAccess can be null if this method is called by the {@link IndexTask}.
+   */
+  public static CachingSegmentAllocator forNonLinearPartitioning(
+      final TaskToolbox toolbox,
+      final String dataSource,
+      final String taskId,
+      final @Nullable SupervisorTaskAccess supervisorTaskAccess,
+      final CompletePartitionAnalysis partitionAnalysis
+  ) throws IOException
+  {
+    return new CachingLocalSegmentAllocator(
+        toolbox,
+        dataSource,
+        taskId,
+        supervisorTaskAccess,
+        partitionAnalysis::convertToIntervalToSegmentIds
+    );
+  }
+
+  private SegmentAllocators()
+  {
+  }
+}

indexing-service/src/main/java/org/apache/druid/indexing/common/task/SequenceNameFunction.java

@@ -23,20 +23,13 @@ import org.apache.druid.data.input.InputRow;
 import org.apache.druid.segment.realtime.appenderator.SegmentAllocator;
 import org.joda.time.Interval;
 
-/**
+public interface SequenceNameFunction
- * Segment allocator interface for {@link IndexTask}. It has 3 different modes for allocating segments.
- */
-public interface IndexTaskSegmentAllocator extends SegmentAllocator
 {
   /**
-   * SequenceName is the key to create the segmentId. If previousSegmentId is given, {@link SegmentAllocator} allocates
+   * The sequence name is to keep track of the row sequences that should be stored in the same segment.
-   * segmentId depending on sequenceName and previousSegmentId. If it's missing, it allocates segmentId using
+   * In other words, given two rows, they should be stored in the same segment if their sequence name is same.
-   * sequenceName and interval. For {@link IndexTask}, it always provides the previousSegmentId to
-   * SegmentAllocator.
-   * See {@link org.apache.druid.metadata.IndexerSQLMetadataStorageCoordinator#allocatePendingSegment} for details.
    *
-   * Implementations should return the correct sequenceName based on the given interval and inputRow, which is passed
+   * @see SegmentAllocator
-   * to SegmentAllocator.
    */
   String getSequenceName(Interval interval, InputRow inputRow);
 }

indexing-service/src/main/java/org/apache/druid/indexing/common/task/SupervisorTaskCoordinatingSegmentAllocator.java

@@ -0,0 +1,56 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.common.task;
+
+import org.apache.druid.data.input.InputRow;
+import org.apache.druid.indexing.common.task.batch.parallel.ParallelIndexSupervisorTaskClient;
+import org.apache.druid.segment.realtime.appenderator.SegmentAllocator;
+import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
+
+import java.io.IOException;
+
+/**
+ * Segment allocator that allocates new segments using the supervisor task per request.
+ */
+public class SupervisorTaskCoordinatingSegmentAllocator implements SegmentAllocator
+{
+  private final String supervisorTaskId;
+  private final ParallelIndexSupervisorTaskClient taskClient;
+
+  SupervisorTaskCoordinatingSegmentAllocator(
+      String supervisorTaskId,
+      ParallelIndexSupervisorTaskClient taskClient
+  )
+  {
+    this.supervisorTaskId = supervisorTaskId;
+    this.taskClient = taskClient;
+  }
+
+  @Override
+  public SegmentIdWithShardSpec allocate(
+      InputRow row,
+      String sequenceName,
+      String previousSegmentId,
+      boolean skipSegmentLineageCheck
+  ) throws IOException
+  {
+    return taskClient.allocateSegment(supervisorTaskId, row.getTimestamp());
+  }
+}

indexing-service/src/main/java/org/apache/druid/indexing/common/task/TaskLockHelper.java

@@ -20,6 +20,7 @@
 package org.apache.druid.indexing.common.task;
 
 import com.google.common.base.Preconditions;
+import org.apache.druid.indexing.common.LockGranularity;
 import org.apache.druid.indexing.common.SegmentLock;
 import org.apache.druid.indexing.common.TaskLockType;
 import org.apache.druid.indexing.common.actions.SegmentLockReleaseAction;
@@ -46,12 +47,20 @@ import java.util.Set;
 import java.util.stream.Collectors;
 
 /**
- * This class provides some methods to use the segment lock easier and caches the information of locked segments.
+ * This class provides 3 functionalities.
+ * - {@link #verifyAndLockExistingSegments} is to verify the granularity of existing segments and lock them.
+ *   This method must be called before the task starts indexing.
+ * - Tells the task what {@link LockGranularity} it should use. Note that the LockGranularity is determined in
+ *   {@link AbstractBatchIndexTask#determineLockGranularityandTryLock}.
+ * - Provides some util methods for {@link LockGranularity#SEGMENT}. Also caches the information of locked segments when
+ *   - the SEGMENt lock granularity is used.
  */
-public class SegmentLockHelper
+public class TaskLockHelper
 {
   private final Map<Interval, OverwritingRootGenerationPartitions> overwritingRootGenPartitions = new HashMap<>();
   private final Set<DataSegment> lockedExistingSegments = new HashSet<>();
+  private final boolean useSegmentLock;
+
   @Nullable
   private Granularity knownSegmentGranularity;
 
@@ -84,6 +93,21 @@ public class SegmentLockHelper
     }
   }
 
+  public TaskLockHelper(boolean useSegmentLock)
+  {
+    this.useSegmentLock = useSegmentLock;
+  }
+
+  public boolean isUseSegmentLock()
+  {
+    return useSegmentLock;
+  }
+
+  public LockGranularity getLockGranularityToUse()
+  {
+    return useSegmentLock ? LockGranularity.SEGMENT : LockGranularity.TIME_CHUNK;
+  }
+
   public boolean hasLockedExistingSegments()
   {
     return !lockedExistingSegments.isEmpty();

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/parallel/ParallelIndexSupervisorTask.java

@@ -58,7 +58,6 @@ import org.apache.druid.indexing.common.task.Task;
 import org.apache.druid.indexing.common.task.TaskResource;
 import org.apache.druid.indexing.common.task.Tasks;
 import org.apache.druid.indexing.common.task.batch.parallel.ParallelIndexTaskRunner.SubTaskSpecStatus;
-import org.apache.druid.indexing.common.task.batch.parallel.distribution.PartitionBoundaries;
 import org.apache.druid.indexing.common.task.batch.parallel.distribution.StringDistribution;
 import org.apache.druid.indexing.common.task.batch.parallel.distribution.StringDistributionMerger;
 import org.apache.druid.indexing.common.task.batch.parallel.distribution.StringSketchMerger;
@@ -81,6 +80,7 @@ import org.apache.druid.server.security.Action;
 import org.apache.druid.server.security.AuthorizerMapper;
 import org.apache.druid.timeline.DataSegment;
 import org.apache.druid.timeline.partition.NumberedShardSpec;
+import org.apache.druid.timeline.partition.PartitionBoundaries;
 import org.apache.druid.utils.CollectionUtils;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.joda.time.DateTime;

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/parallel/ParallelIndexTuningConfig.java

@@ -24,6 +24,7 @@ import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.common.base.Preconditions;
 import org.apache.druid.data.input.SplitHintSpec;
 import org.apache.druid.indexer.partitions.PartitionsSpec;
+import org.apache.druid.indexer.partitions.SingleDimensionPartitionsSpec;
 import org.apache.druid.indexing.common.task.IndexTask.IndexTuningConfig;
 import org.apache.druid.java.util.common.IAE;
 import org.apache.druid.segment.IndexSpec;
@@ -185,6 +186,11 @@ public class ParallelIndexTuningConfig extends IndexTuningConfig
     Preconditions.checkArgument(this.maxNumConcurrentSubTasks > 0, "maxNumConcurrentSubTasks must be positive");
     Preconditions.checkArgument(this.maxNumSegmentsToMerge > 0, "maxNumSegmentsToMerge must be positive");
     Preconditions.checkArgument(this.totalNumMergeTasks > 0, "totalNumMergeTasks must be positive");
+    if (getPartitionsSpec() != null && getPartitionsSpec() instanceof SingleDimensionPartitionsSpec) {
+      if (((SingleDimensionPartitionsSpec) getPartitionsSpec()).getPartitionDimension() == null) {
+        throw new IAE("partitionDimension must be specified");
+      }
+    }
   }
 
   @Nullable

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/parallel/PartialHashSegmentGenerateTask.java

@@ -26,22 +26,24 @@ import org.apache.druid.client.indexing.IndexingServiceClient;
 import org.apache.druid.indexer.partitions.HashedPartitionsSpec;
 import org.apache.druid.indexing.common.TaskToolbox;
 import org.apache.druid.indexing.common.actions.TaskActionClient;
-import org.apache.druid.indexing.common.task.HashPartitionCachingLocalSegmentAllocator;
+import org.apache.druid.indexing.common.task.CachingSegmentAllocator;
 import org.apache.druid.indexing.common.task.IndexTaskClientFactory;
-import org.apache.druid.indexing.common.task.IndexTaskSegmentAllocator;
+import org.apache.druid.indexing.common.task.SegmentAllocators;
 import org.apache.druid.indexing.common.task.TaskResource;
 import org.apache.druid.indexing.common.task.batch.parallel.iterator.DefaultIndexTaskInputRowIteratorBuilder;
-import org.apache.druid.java.util.common.Pair;
+import org.apache.druid.indexing.common.task.batch.partition.HashPartitionAnalysis;
 import org.apache.druid.segment.indexing.granularity.GranularitySpec;
 import org.apache.druid.segment.realtime.appenderator.AppenderatorsManager;
 import org.apache.druid.timeline.DataSegment;
-import org.apache.druid.timeline.partition.ShardSpecFactory;
+import org.apache.druid.timeline.partition.PartialShardSpec;
 import org.joda.time.Interval;
 
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.io.IOException;
 import java.util.List;
 import java.util.Map;
+import java.util.SortedSet;
 import java.util.stream.Collectors;
 
 /**
@@ -125,14 +127,18 @@ public class PartialHashSegmentGenerateTask extends PartialSegmentGenerateTask<G
   }
 
   @Override
-  IndexTaskSegmentAllocator createSegmentAllocator(TaskToolbox toolbox) throws IOException
+  CachingSegmentAllocator createSegmentAllocator(TaskToolbox toolbox, ParallelIndexSupervisorTaskClient taskClient)
+      throws IOException
   {
-    return new HashPartitionCachingLocalSegmentAllocator(
+    final GranularitySpec granularitySpec = ingestionSchema.getDataSchema().getGranularitySpec();
+    final ParallelIndexTuningConfig tuningConfig = ingestionSchema.getTuningConfig();
+    final HashedPartitionsSpec partitionsSpec = (HashedPartitionsSpec) tuningConfig.getGivenOrDefaultPartitionsSpec();
+    return SegmentAllocators.forNonLinearPartitioning(
         toolbox,
-        getId(),
-        supervisorTaskId,
         getDataSource(),
-        createShardSpecs()
+        getId(),
+        new SupervisorTaskAccess(supervisorTaskId, taskClient),
+        createHashPartitionAnalysisFromPartitionsSpec(granularitySpec, partitionsSpec)
     );
   }
 
@@ -158,17 +164,24 @@ public class PartialHashSegmentGenerateTask extends PartialSegmentGenerateTask<G
     );
   }
 
-  private Map<Interval, Pair<ShardSpecFactory, Integer>> createShardSpecs()
+  /**
+   * Creates shard specs based on the given configurations. The return value is a map between intervals created
+   * based on the segment granularity and the shard specs to be created.
+   * Note that the shard specs to be created is a pair of {@link PartialShardSpec} and number of segments per interval
+   * and filled only when {@link #isGuaranteedRollup} = true. Otherwise, the return value contains only the set of
+   * intervals generated based on the segment granularity.
+   */
+  public static HashPartitionAnalysis createHashPartitionAnalysisFromPartitionsSpec(
+      GranularitySpec granularitySpec,
+      @Nonnull HashedPartitionsSpec partitionsSpec
+  )
   {
-    GranularitySpec granularitySpec = ingestionSchema.getDataSchema().getGranularitySpec();
+    final SortedSet<Interval> intervals = granularitySpec.bucketIntervals().get();
-    final ParallelIndexTuningConfig tuningConfig = ingestionSchema.getTuningConfig();
+    final int numBucketsPerInterval = partitionsSpec.getNumShards() == null
-    final HashedPartitionsSpec partitionsSpec = (HashedPartitionsSpec) tuningConfig.getGivenOrDefaultPartitionsSpec();
+                                      ? 1
-
+                                      : partitionsSpec.getNumShards();
-    return createShardSpecWithoutInputScan(
+    final HashPartitionAnalysis partitionAnalysis = new HashPartitionAnalysis(partitionsSpec);
-        granularitySpec,
+    intervals.forEach(interval -> partitionAnalysis.updateBucket(interval, numBucketsPerInterval));
-        ingestionSchema.getIOConfig(),
+    return partitionAnalysis;
-        tuningConfig,
-        partitionsSpec
-    );
   }
 }

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/parallel/PartialRangeSegmentGenerateParallelIndexTaskRunner.java

@@ -24,8 +24,8 @@ import org.apache.druid.client.indexing.IndexingServiceClient;
 import org.apache.druid.data.input.InputSplit;
 import org.apache.druid.indexing.common.TaskToolbox;
 import org.apache.druid.indexing.common.task.IndexTaskClientFactory;
-import org.apache.druid.indexing.common.task.batch.parallel.distribution.PartitionBoundaries;
 import org.apache.druid.segment.realtime.appenderator.AppenderatorsManager;
+import org.apache.druid.timeline.partition.PartitionBoundaries;
 import org.joda.time.Interval;
 
 import java.util.Map;

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/parallel/PartialRangeSegmentGenerateTask.java

@@ -28,15 +28,16 @@ import org.apache.druid.indexer.partitions.PartitionsSpec;
 import org.apache.druid.indexer.partitions.SingleDimensionPartitionsSpec;
 import org.apache.druid.indexing.common.TaskToolbox;
 import org.apache.druid.indexing.common.actions.TaskActionClient;
+import org.apache.druid.indexing.common.task.CachingSegmentAllocator;
 import org.apache.druid.indexing.common.task.IndexTaskClientFactory;
-import org.apache.druid.indexing.common.task.IndexTaskSegmentAllocator;
+import org.apache.druid.indexing.common.task.SegmentAllocators;
-import org.apache.druid.indexing.common.task.RangePartitionCachingLocalSegmentAllocator;
 import org.apache.druid.indexing.common.task.TaskResource;
-import org.apache.druid.indexing.common.task.batch.parallel.distribution.PartitionBoundaries;
 import org.apache.druid.indexing.common.task.batch.parallel.iterator.RangePartitionIndexTaskInputRowIteratorBuilder;
+import org.apache.druid.indexing.common.task.batch.partition.RangePartitionAnalysis;
 import org.apache.druid.indexing.worker.ShuffleDataSegmentPusher;
 import org.apache.druid.segment.realtime.appenderator.AppenderatorsManager;
 import org.apache.druid.timeline.DataSegment;
+import org.apache.druid.timeline.partition.PartitionBoundaries;
 import org.joda.time.Interval;
 
 import javax.annotation.Nullable;
@@ -149,15 +150,19 @@ public class PartialRangeSegmentGenerateTask extends PartialSegmentGenerateTask<
   }
 
   @Override
-  IndexTaskSegmentAllocator createSegmentAllocator(TaskToolbox toolbox) throws IOException
+  CachingSegmentAllocator createSegmentAllocator(TaskToolbox toolbox, ParallelIndexSupervisorTaskClient taskClient)
+      throws IOException
   {
-    return new RangePartitionCachingLocalSegmentAllocator(
+    final RangePartitionAnalysis partitionAnalysis = new RangePartitionAnalysis(
+        (SingleDimensionPartitionsSpec) ingestionSchema.getTuningConfig().getPartitionsSpec()
+    );
+    intervalToPartitions.forEach(partitionAnalysis::updateBucket);
+    return SegmentAllocators.forNonLinearPartitioning(
         toolbox,
-        getId(),
-        supervisorTaskId,
         getDataSource(),
-        getPartitionDimension(ingestionSchema),
+        getId(),
-        intervalToPartitions
+        new SupervisorTaskAccess(supervisorTaskId, taskClient),
+        partitionAnalysis
     );
   }
 

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/parallel/PartialSegmentGenerateTask.java

@@ -28,10 +28,12 @@ import org.apache.druid.indexing.common.TaskToolbox;
 import org.apache.druid.indexing.common.stats.DropwizardRowIngestionMeters;
 import org.apache.druid.indexing.common.stats.RowIngestionMeters;
 import org.apache.druid.indexing.common.task.BatchAppenderators;
+import org.apache.druid.indexing.common.task.CachingSegmentAllocator;
 import org.apache.druid.indexing.common.task.ClientBasedTaskInfoProvider;
 import org.apache.druid.indexing.common.task.IndexTaskClientFactory;
-import org.apache.druid.indexing.common.task.IndexTaskSegmentAllocator;
 import org.apache.druid.indexing.common.task.InputSourceProcessor;
+import org.apache.druid.indexing.common.task.NonLinearlyPartitionedSequenceNameFunction;
+import org.apache.druid.indexing.common.task.SequenceNameFunction;
 import org.apache.druid.indexing.common.task.TaskResource;
 import org.apache.druid.indexing.common.task.Tasks;
 import org.apache.druid.indexing.common.task.batch.parallel.iterator.IndexTaskInputRowIteratorBuilder;
@@ -45,6 +47,7 @@ import org.apache.druid.segment.realtime.RealtimeMetricsMonitor;
 import org.apache.druid.segment.realtime.appenderator.Appenderator;
 import org.apache.druid.segment.realtime.appenderator.AppenderatorsManager;
 import org.apache.druid.segment.realtime.appenderator.BatchAppenderatorDriver;
+import org.apache.druid.segment.realtime.appenderator.SegmentAllocator;
 import org.apache.druid.segment.realtime.appenderator.SegmentsAndCommitMetadata;
 import org.apache.druid.timeline.DataSegment;
 
@@ -117,16 +120,19 @@ abstract class PartialSegmentGenerateTask<T extends GeneratedPartitionsReport> e
         ingestionSchema.getTuningConfig().getChatHandlerNumRetries()
     );
 
-    final List<DataSegment> segments = generateSegments(toolbox, inputSource, tmpDir);
+    final List<DataSegment> segments = generateSegments(toolbox, taskClient, inputSource, tmpDir);
     taskClient.report(supervisorTaskId, createGeneratedPartitionsReport(toolbox, segments));
 
     return TaskStatus.success(getId());
   }
 
   /**
-   * @return {@link IndexTaskSegmentAllocator} suitable for the desired segment partitioning strategy.
+   * @return {@link SegmentAllocator} suitable for the desired segment partitioning strategy.
    */
-  abstract IndexTaskSegmentAllocator createSegmentAllocator(TaskToolbox toolbox) throws IOException;
+  abstract CachingSegmentAllocator createSegmentAllocator(
+      TaskToolbox toolbox,
+      ParallelIndexSupervisorTaskClient taskClient
+  ) throws IOException;
 
   /**
    * @return {@link GeneratedPartitionsReport} suitable for the desired segment partitioning strategy.
@@ -138,6 +144,7 @@ abstract class PartialSegmentGenerateTask<T extends GeneratedPartitionsReport> e
 
   private List<DataSegment> generateSegments(
       final TaskToolbox toolbox,
+      final ParallelIndexSupervisorTaskClient taskClient,
       final InputSource inputSource,
       final File tmpDir
   ) throws IOException, InterruptedException, ExecutionException, TimeoutException
@@ -164,7 +171,11 @@ abstract class PartialSegmentGenerateTask<T extends GeneratedPartitionsReport> e
     final PartitionsSpec partitionsSpec = tuningConfig.getGivenOrDefaultPartitionsSpec();
     final long pushTimeout = tuningConfig.getPushTimeout();
 
-    final IndexTaskSegmentAllocator segmentAllocator = createSegmentAllocator(toolbox);
+    final CachingSegmentAllocator segmentAllocator = createSegmentAllocator(toolbox, taskClient);
+    final SequenceNameFunction sequenceNameFunction = new NonLinearlyPartitionedSequenceNameFunction(
+        getId(),
+        segmentAllocator.getShardSpecs()
+    );
 
     final Appenderator appenderator = BatchAppenderators.newAppenderator(
         getId(),
@@ -195,7 +206,7 @@ abstract class PartialSegmentGenerateTask<T extends GeneratedPartitionsReport> e
           inputSource,
           inputSource.needsFormat() ? ParallelIndexSupervisorTask.getInputFormat(ingestionSchema) : null,
           tmpDir,
-          segmentAllocator
+          sequenceNameFunction
       );
 
       return pushed.getSegments();

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/parallel/SinglePhaseSubTask.java

@@ -22,7 +22,6 @@ package org.apache.druid.indexing.common.task.batch.parallel;
 import com.fasterxml.jackson.annotation.JacksonInject;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
-import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Optional;
 import org.apache.commons.io.FileUtils;
 import org.apache.druid.client.indexing.IndexingServiceClient;
@@ -32,19 +31,14 @@ import org.apache.druid.data.input.InputSource;
 import org.apache.druid.data.input.InputSourceReader;
 import org.apache.druid.indexer.TaskStatus;
 import org.apache.druid.indexer.partitions.DynamicPartitionsSpec;
-import org.apache.druid.indexing.appenderator.ActionBasedSegmentAllocator;
-import org.apache.druid.indexing.common.LockGranularity;
 import org.apache.druid.indexing.common.TaskToolbox;
-import org.apache.druid.indexing.common.actions.SegmentAllocateAction;
-import org.apache.druid.indexing.common.actions.SurrogateAction;
 import org.apache.druid.indexing.common.actions.TaskActionClient;
 import org.apache.druid.indexing.common.task.AbstractBatchIndexTask;
 import org.apache.druid.indexing.common.task.BatchAppenderators;
 import org.apache.druid.indexing.common.task.ClientBasedTaskInfoProvider;
 import org.apache.druid.indexing.common.task.IndexTask;
 import org.apache.druid.indexing.common.task.IndexTaskClientFactory;
-import org.apache.druid.indexing.common.task.SegmentLockHelper;
+import org.apache.druid.indexing.common.task.SegmentAllocators;
-import org.apache.druid.indexing.common.task.SegmentLockHelper.OverwritingRootGenerationPartitions;
 import org.apache.druid.indexing.common.task.TaskResource;
 import org.apache.druid.indexing.common.task.Tasks;
 import org.apache.druid.java.util.common.ISE;
@@ -69,14 +63,10 @@ import org.apache.druid.segment.realtime.appenderator.AppenderatorsManager;
 import org.apache.druid.segment.realtime.appenderator.BaseAppenderatorDriver;
 import org.apache.druid.segment.realtime.appenderator.BatchAppenderatorDriver;
 import org.apache.druid.segment.realtime.appenderator.SegmentAllocator;
-import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
 import org.apache.druid.segment.realtime.appenderator.SegmentsAndCommitMetadata;
 import org.apache.druid.timeline.DataSegment;
 import org.apache.druid.timeline.VersionedIntervalTimeline;
-import org.apache.druid.timeline.partition.NumberedOverwritingShardSpecFactory;
-import org.apache.druid.timeline.partition.NumberedShardSpecFactory;
 import org.apache.druid.timeline.partition.PartitionChunk;
-import org.apache.druid.timeline.partition.ShardSpecFactory;
 import org.joda.time.Interval;
 
 import javax.annotation.Nullable;
@@ -230,7 +220,7 @@ public class SinglePhaseSubTask extends AbstractBatchIndexTask
     );
 
     // Find inputSegments overshadowed by pushedSegments
-    final Set<DataSegment> allSegments = new HashSet<>(getSegmentLockHelper().getLockedExistingSegments());
+    final Set<DataSegment> allSegments = new HashSet<>(getTaskLockHelper().getLockedExistingSegments());
     allSegments.addAll(pushedSegments);
     final VersionedIntervalTimeline<String, DataSegment> timeline = VersionedIntervalTimeline.forSegments(allSegments);
     final Set<DataSegment> oldSegments = timeline.findFullyOvershadowed()
@@ -279,93 +269,6 @@ public class SinglePhaseSubTask extends AbstractBatchIndexTask
     }
   }
 
-  @VisibleForTesting
-  SegmentAllocator createSegmentAllocator(TaskToolbox toolbox, ParallelIndexSupervisorTaskClient taskClient)
-  {
-    return new WrappingSegmentAllocator(toolbox, taskClient);
-  }
-
-  private class WrappingSegmentAllocator implements SegmentAllocator
-  {
-    private final TaskToolbox toolbox;
-    private final ParallelIndexSupervisorTaskClient taskClient;
-
-    private SegmentAllocator internalAllocator;
-
-    private WrappingSegmentAllocator(TaskToolbox toolbox, ParallelIndexSupervisorTaskClient taskClient)
-    {
-      this.toolbox = toolbox;
-      this.taskClient = taskClient;
-    }
-
-    @Override
-    public SegmentIdWithShardSpec allocate(
-        InputRow row,
-        String sequenceName,
-        String previousSegmentId,
-        boolean skipSegmentLineageCheck
-    ) throws IOException
-    {
-      if (internalAllocator == null) {
-        internalAllocator = createSegmentAllocator();
-      }
-      return internalAllocator.allocate(row, sequenceName, previousSegmentId, skipSegmentLineageCheck);
-    }
-
-    private SegmentAllocator createSegmentAllocator()
-    {
-      final GranularitySpec granularitySpec = ingestionSchema.getDataSchema().getGranularitySpec();
-      final SegmentLockHelper segmentLockHelper = getSegmentLockHelper();
-      if (ingestionSchema.getIOConfig().isAppendToExisting() || isUseSegmentLock()) {
-        return new ActionBasedSegmentAllocator(
-            toolbox.getTaskActionClient(),
-            ingestionSchema.getDataSchema(),
-            (schema, row, sequenceName, previousSegmentId, skipSegmentLineageCheck) -> {
-              final Interval interval = granularitySpec
-                  .bucketInterval(row.getTimestamp())
-                  .or(granularitySpec.getSegmentGranularity().bucket(row.getTimestamp()));
-
-              final ShardSpecFactory shardSpecFactory;
-              if (segmentLockHelper.hasOverwritingRootGenerationPartition(interval)) {
-                final OverwritingRootGenerationPartitions overwritingSegmentMeta = segmentLockHelper
-                    .getOverwritingRootGenerationPartition(interval);
-                if (overwritingSegmentMeta == null) {
-                  throw new ISE("Can't find overwritingSegmentMeta for interval[%s]", interval);
-                }
-                shardSpecFactory = new NumberedOverwritingShardSpecFactory(
-                    overwritingSegmentMeta.getStartRootPartitionId(),
-                    overwritingSegmentMeta.getEndRootPartitionId(),
-                    overwritingSegmentMeta.getMinorVersionForNewSegments()
-                );
-              } else {
-                shardSpecFactory = NumberedShardSpecFactory.instance();
-              }
-
-              return new SurrogateAction<>(
-                  supervisorTaskId,
-                  new SegmentAllocateAction(
-                      schema.getDataSource(),
-                      row.getTimestamp(),
-                      schema.getGranularitySpec().getQueryGranularity(),
-                      schema.getGranularitySpec().getSegmentGranularity(),
-                      sequenceName,
-                      previousSegmentId,
-                      skipSegmentLineageCheck,
-                      shardSpecFactory,
-                      isUseSegmentLock() ? LockGranularity.SEGMENT : LockGranularity.TIME_CHUNK
-                  )
-              );
-            }
-        );
-      } else {
-        return (row, sequenceName, previousSegmentId, skipSegmentLineageCheck) -> taskClient.allocateSegment(
-            supervisorTaskId,
-            row.getTimestamp()
-        );
-      }
-    }
-  }
-
   /**
    * This method reads input data row by row and adds the read row to a proper segment using {@link BaseAppenderatorDriver}.
    * If there is no segment for the row, a new one is created.  Segments can be published in the middle of reading inputs
@@ -410,7 +313,14 @@ public class SinglePhaseSubTask extends AbstractBatchIndexTask
     final DynamicPartitionsSpec partitionsSpec = (DynamicPartitionsSpec) tuningConfig.getGivenOrDefaultPartitionsSpec();
     final long pushTimeout = tuningConfig.getPushTimeout();
     final boolean explicitIntervals = granularitySpec.bucketIntervals().isPresent();
-    final SegmentAllocator segmentAllocator = createSegmentAllocator(toolbox, taskClient);
+    final SegmentAllocator segmentAllocator = SegmentAllocators.forLinearPartitioning(
+        toolbox,
+        new SupervisorTaskAccess(getSupervisorTaskId(), taskClient),
+        getIngestionSchema().getDataSchema(),
+        getTaskLockHelper(),
+        ingestionSchema.getIOConfig().isAppendToExisting(),
+        partitionsSpec
+    );
 
     final Appenderator appenderator = BatchAppenderators.newAppenderator(
         getId(),

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/parallel/SupervisorTaskAccess.java

@@ -0,0 +1,50 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.common.task.batch.parallel;
+
+/**
+ * Simple POJO to hold the information of the supervisor task.
+ *
+ * @see ParallelIndexSupervisorTask
+ */
+public class SupervisorTaskAccess
+{
+  private final String supervisorTaskId;
+  private final ParallelIndexSupervisorTaskClient taskClient;
+
+  public SupervisorTaskAccess(
+      String supervisorTaskId,
+      ParallelIndexSupervisorTaskClient taskClient
+  )
+  {
+    this.supervisorTaskId = supervisorTaskId;
+    this.taskClient = taskClient;
+  }
+
+  public String getSupervisorTaskId()
+  {
+    return supervisorTaskId;
+  }
+
+  public ParallelIndexSupervisorTaskClient getTaskClient()
+  {
+    return taskClient;
+  }
+}

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/parallel/distribution/StringDistribution.java

@@ -21,6 +21,7 @@ package org.apache.druid.indexing.common.task.batch.parallel.distribution;
 
 import com.fasterxml.jackson.annotation.JsonSubTypes;
 import com.fasterxml.jackson.annotation.JsonTypeInfo;
+import org.apache.druid.timeline.partition.PartitionBoundaries;
 
 /**
  * Counts frequencies of {@link String}s.

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/parallel/distribution/StringSketch.java

@@ -34,6 +34,7 @@ import com.google.common.base.Preconditions;
 import org.apache.datasketches.ArrayOfStringsSerDe;
 import org.apache.datasketches.memory.Memory;
 import org.apache.datasketches.quantiles.ItemsSketch;
+import org.apache.druid.timeline.partition.PartitionBoundaries;
 
 import java.io.IOException;
 import java.util.Comparator;

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/partition/CompletePartitionAnalysis.java

@@ -0,0 +1,43 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.common.task.batch.partition;
+
+import org.apache.druid.indexer.partitions.PartitionsSpec;
+import org.apache.druid.indexing.common.TaskToolbox;
+import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
+import org.joda.time.Interval;
+
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+
+/**
+ * This interface represents the PartitionAnalysis that has the complete picture of secondary partitions to create.
+ * This type of PartitionAnalysis can be used for the hash or range partitioning in which all secondary partitions
+ * should be determined when the analysis is done.
+ */
+public interface CompletePartitionAnalysis<T, P extends PartitionsSpec> extends PartitionAnalysis<T, P>
+{
+  Map<Interval, List<SegmentIdWithShardSpec>> convertToIntervalToSegmentIds(
+      TaskToolbox toolbox,
+      String dataSource,
+      Function<Interval, String> versionFinder
+  );
+}

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/partition/HashPartitionAnalysis.java

@@ -0,0 +1,128 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.common.task.batch.partition;
+
+import com.google.common.collect.Maps;
+import org.apache.druid.indexer.partitions.HashedPartitionsSpec;
+import org.apache.druid.indexing.common.TaskToolbox;
+import org.apache.druid.java.util.common.IAE;
+import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
+import org.apache.druid.timeline.partition.HashBasedNumberedShardSpec;
+import org.joda.time.Interval;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.function.BiConsumer;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+public class HashPartitionAnalysis implements CompletePartitionAnalysis<Integer, HashedPartitionsSpec>
+{
+  /**
+   * Key is the time ranges for the primary partitioning.
+   * Value is the number of partitions per time range for the secondary partitioning
+   */
+  private final Map<Interval, Integer> intervalToNumBuckets = new HashMap<>();
+  private final HashedPartitionsSpec partitionsSpec;
+
+  public HashPartitionAnalysis(HashedPartitionsSpec partitionsSpec)
+  {
+    this.partitionsSpec = partitionsSpec;
+  }
+
+  @Override
+  public HashedPartitionsSpec getPartitionsSpec()
+  {
+    return partitionsSpec;
+  }
+
+  @Override
+  public void updateBucket(Interval interval, Integer bucketAnalysis)
+  {
+    intervalToNumBuckets.put(interval, bucketAnalysis);
+  }
+
+  @Override
+  public Integer getBucketAnalysis(Interval interval)
+  {
+    final Integer bucketAnalysis = intervalToNumBuckets.get(interval);
+    if (bucketAnalysis == null) {
+      throw new IAE("Missing bucket analysis for interval[%s]", interval);
+    } else {
+      return bucketAnalysis;
+    }
+  }
+
+  @Override
+  public Set<Interval> getAllIntervalsToIndex()
+  {
+    return Collections.unmodifiableSet(intervalToNumBuckets.keySet());
+  }
+
+  @Override
+  public int getNumTimePartitions()
+  {
+    return intervalToNumBuckets.size();
+  }
+
+  public void forEach(BiConsumer<Interval, Integer> consumer)
+  {
+    intervalToNumBuckets.forEach(consumer);
+  }
+
+  @Override
+  public Map<Interval, List<SegmentIdWithShardSpec>> convertToIntervalToSegmentIds(
+      TaskToolbox toolbox,
+      String dataSource,
+      Function<Interval, String> versionFinder
+  )
+  {
+    final Map<Interval, List<SegmentIdWithShardSpec>> intervalToSegmentIds =
+        Maps.newHashMapWithExpectedSize(getNumTimePartitions());
+
+    forEach((interval, numBuckets) -> {
+      intervalToSegmentIds.put(
+          interval,
+          IntStream.range(0, numBuckets)
+                   .mapToObj(i -> {
+                     final HashBasedNumberedShardSpec shardSpec = new HashBasedNumberedShardSpec(
+                         i,
+                         numBuckets,
+                         partitionsSpec.getPartitionDimensions(),
+                         toolbox.getJsonMapper()
+                     );
+                     return new SegmentIdWithShardSpec(
+                         dataSource,
+                         interval,
+                         versionFinder.apply(interval),
+                         shardSpec
+                     );
+                   })
+                   .collect(Collectors.toList())
+      );
+    });
+
+    return intervalToSegmentIds;
+  }
+}

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/partition/LinearPartitionAnalysis.java

@@ -0,0 +1,78 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.common.task.batch.partition;
+
+import com.google.common.base.Preconditions;
+import org.apache.druid.indexer.partitions.DynamicPartitionsSpec;
+import org.apache.druid.java.util.common.IAE;
+import org.joda.time.Interval;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Partition analysis for the linear partitioning. This analysis is not complete because, in the linear partitioning,
+ * segments are partitioned by their size which means they will be allocated dynamically during the indexing.
+ */
+public class LinearPartitionAnalysis implements PartitionAnalysis<Integer, DynamicPartitionsSpec>
+{
+  private final Set<Interval> intervals = new HashSet<>();
+  private final DynamicPartitionsSpec partitionsSpec;
+
+  public LinearPartitionAnalysis(DynamicPartitionsSpec partitionsSpec)
+  {
+    this.partitionsSpec = partitionsSpec;
+  }
+
+  @Override
+  public DynamicPartitionsSpec getPartitionsSpec()
+  {
+    return partitionsSpec;
+  }
+
+  @Override
+  public void updateBucket(Interval interval, Integer bucketAnalysis)
+  {
+    Preconditions.checkArgument(bucketAnalysis == 1, "There should be only one bucket with linear partitioining");
+    intervals.add(interval);
+  }
+
+  @Override
+  public Integer getBucketAnalysis(Interval interval)
+  {
+    if (intervals.contains(interval)) {
+      return 1;
+    } else {
+      throw new IAE("Missing bucket analysis for interval[%s]", interval);
+    }
+  }
+
+  @Override
+  public Set<Interval> getAllIntervalsToIndex()
+  {
+    return intervals;
+  }
+
+  @Override
+  public int getNumTimePartitions()
+  {
+    return intervals.size();
+  }
+}

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/partition/PartitionAnalysis.java

@@ -0,0 +1,50 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.common.task.batch.partition;
+
+import org.apache.druid.indexer.partitions.PartitionsSpec;
+import org.joda.time.Interval;
+
+import java.util.Set;
+
+/**
+ * Analysis of the partitions to create. The implementation is mutable and updated by the indexing
+ * {@link org.apache.druid.indexing.common.task.Task}.
+ *
+ * This interface provides all time chunks for the primary partitioning and the bucket information per time chunk
+ * for the secondary partitioning.
+ */
+public interface PartitionAnalysis<T, P extends PartitionsSpec>
+{
+  P getPartitionsSpec();
+
+  void updateBucket(Interval interval, T bucketAnalysis);
+
+  /**
+   * Returns the analysis of the secondary bucket for the given time chunk.
+   *
+   * @throws IllegalArgumentException if the bucket analysis is missing for the given interval
+   */
+  T getBucketAnalysis(Interval interval);
+
+  Set<Interval> getAllIntervalsToIndex();
+
+  int getNumTimePartitions();
+}

indexing-service/src/main/java/org/apache/druid/indexing/common/task/batch/partition/RangePartitionAnalysis.java

@@ -0,0 +1,174 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.common.task.batch.partition;
+
+import com.google.common.collect.Maps;
+import org.apache.druid.indexer.partitions.SingleDimensionPartitionsSpec;
+import org.apache.druid.indexing.common.TaskToolbox;
+import org.apache.druid.java.util.common.IAE;
+import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
+import org.apache.druid.timeline.partition.PartitionBoundaries;
+import org.apache.druid.timeline.partition.SingleDimensionShardSpec;
+import org.joda.time.Interval;
+
+import javax.annotation.Nullable;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.function.BiConsumer;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+public class RangePartitionAnalysis
+    implements CompletePartitionAnalysis<PartitionBoundaries, SingleDimensionPartitionsSpec>
+{
+  private final Map<Interval, PartitionBoundaries> intervalToPartitionBoundaries = new HashMap<>();
+  private final SingleDimensionPartitionsSpec partitionsSpec;
+
+  public RangePartitionAnalysis(SingleDimensionPartitionsSpec partitionsSpec)
+  {
+    this.partitionsSpec = partitionsSpec;
+  }
+
+  @Override
+  public SingleDimensionPartitionsSpec getPartitionsSpec()
+  {
+    return partitionsSpec;
+  }
+
+  @Override
+  public void updateBucket(Interval interval, PartitionBoundaries bucketAnalysis)
+  {
+    intervalToPartitionBoundaries.put(interval, bucketAnalysis);
+  }
+
+  @Override
+  public PartitionBoundaries getBucketAnalysis(Interval interval)
+  {
+    final PartitionBoundaries bucketAnalysis = intervalToPartitionBoundaries.get(interval);
+    if (bucketAnalysis == null) {
+      throw new IAE("Missing bucket analysis for interval[%s]", interval);
+    } else {
+      return bucketAnalysis;
+    }
+  }
+
+  @Override
+  public Set<Interval> getAllIntervalsToIndex()
+  {
+    return Collections.unmodifiableSet(intervalToPartitionBoundaries.keySet());
+  }
+
+  private void forEach(BiConsumer<Interval, PartitionBoundaries> consumer)
+  {
+    intervalToPartitionBoundaries.forEach(consumer);
+  }
+
+  @Override
+  public int getNumTimePartitions()
+  {
+    return intervalToPartitionBoundaries.size();
+  }
+
+  @Override
+  public Map<Interval, List<SegmentIdWithShardSpec>> convertToIntervalToSegmentIds(
+      TaskToolbox toolbox,
+      String dataSource,
+      Function<Interval, String> versionFinder
+  )
+  {
+    final String partitionDimension = partitionsSpec.getPartitionDimension();
+    final Map<Interval, List<SegmentIdWithShardSpec>> intervalToSegmentIds = Maps.newHashMapWithExpectedSize(
+        getNumTimePartitions()
+    );
+
+    forEach((interval, partitionBoundaries) ->
+                intervalToSegmentIds.put(
+                    interval,
+                    translatePartitionBoundaries(
+                        dataSource,
+                        interval,
+                        partitionDimension,
+                        partitionBoundaries,
+                        versionFinder
+                    )
+                )
+    );
+
+    return intervalToSegmentIds;
+  }
+
+  /**
+   * Translate {@link PartitionBoundaries} into the corresponding
+   * {@link SingleDimensionPartitionsSpec} with segment id.
+   */
+  private static List<SegmentIdWithShardSpec> translatePartitionBoundaries(
+      String dataSource,
+      Interval interval,
+      String partitionDimension,
+      PartitionBoundaries partitionBoundaries,
+      Function<Interval, String> versionFinder
+  )
+  {
+    if (partitionBoundaries.isEmpty()) {
+      return Collections.emptyList();
+    }
+
+    return IntStream.range(0, partitionBoundaries.size() - 1)
+                    .mapToObj(i -> createSegmentIdWithShardSpec(
+                        dataSource,
+                        interval,
+                        versionFinder.apply(interval),
+                        partitionDimension,
+                        partitionBoundaries.get(i),
+                        partitionBoundaries.get(i + 1),
+                        i
+                    ))
+                    .collect(Collectors.toList());
+  }
+
+  private static SegmentIdWithShardSpec createSegmentIdWithShardSpec(
+      String dataSource,
+      Interval interval,
+      String version,
+      String partitionDimension,
+      String partitionStart,
+      @Nullable String partitionEnd,
+      int partitionNum
+  )
+  {
+    // The shardSpec created here will be reused in PartialGenericSegmentMergeTask. This is ok because
+    // all PartialSegmentGenerateTasks create the same set of segmentIds (and thus shardSpecs).
+    return new SegmentIdWithShardSpec(
+        dataSource,
+        interval,
+        version,
+        new SingleDimensionShardSpec(
+            partitionDimension,
+            partitionStart,
+            partitionEnd,
+            partitionNum
+        )
+    );
+  }
+}

indexing-service/src/main/java/org/apache/druid/indexing/overlord/LockRequestForNewSegment.java

@@ -25,7 +25,7 @@ import org.apache.druid.indexing.common.TaskLock;
 import org.apache.druid.indexing.common.TaskLockType;
 import org.apache.druid.indexing.common.task.Task;
 import org.apache.druid.java.util.common.DateTimes;
-import org.apache.druid.timeline.partition.ShardSpecFactory;
+import org.apache.druid.timeline.partition.PartialShardSpec;
 import org.joda.time.Interval;
 
 import javax.annotation.Nullable;
@@ -37,7 +37,7 @@ public class LockRequestForNewSegment implements LockRequest
   private final String groupId;
   private final String dataSource;
   private final Interval interval;
-  private final ShardSpecFactory shardSpecFactory;
+  private final PartialShardSpec partialShardSpec;
   private final int priority;
   private final String sequenceName;
   @Nullable
@@ -52,7 +52,7 @@ public class LockRequestForNewSegment implements LockRequest
       String groupId,
       String dataSource,
       Interval interval,
-      ShardSpecFactory shardSpecFactory,
+      PartialShardSpec partialShardSpec,
       int priority,
       String sequenceName,
       @Nullable String previsousSegmentId,
@@ -64,7 +64,7 @@ public class LockRequestForNewSegment implements LockRequest
     this.groupId = groupId;
     this.dataSource = dataSource;
     this.interval = interval;
-    this.shardSpecFactory = shardSpecFactory;
+    this.partialShardSpec = partialShardSpec;
     this.priority = priority;
     this.sequenceName = sequenceName;
     this.previsousSegmentId = previsousSegmentId;
@@ -77,7 +77,7 @@ public class LockRequestForNewSegment implements LockRequest
       TaskLockType lockType,
       Task task,
       Interval interval,
-      ShardSpecFactory shardSpecFactory,
+      PartialShardSpec partialShardSpec,
       String sequenceName,
       @Nullable String previsousSegmentId,
       boolean skipSegmentLineageCheck
@@ -89,7 +89,7 @@ public class LockRequestForNewSegment implements LockRequest
         task.getGroupId(),
         task.getDataSource(),
         interval,
-        shardSpecFactory,
+        partialShardSpec,
         task.getPriority(),
         sequenceName,
         previsousSegmentId,
@@ -133,9 +133,9 @@ public class LockRequestForNewSegment implements LockRequest
     return priority;
   }
 
-  public ShardSpecFactory getShardSpecFactory()
+  public PartialShardSpec getPartialShardSpec()
   {
-    return shardSpecFactory;
+    return partialShardSpec;
   }
 
   @Override
@@ -187,7 +187,7 @@ public class LockRequestForNewSegment implements LockRequest
            ", groupId='" + groupId + '\'' +
            ", dataSource='" + dataSource + '\'' +
            ", interval=" + interval +
-           ", shardSpecFactory=" + shardSpecFactory +
+           ", partialShardSpec=" + partialShardSpec +
            ", priority=" + priority +
            ", sequenceName='" + sequenceName + '\'' +
            ", previsousSegmentId='" + previsousSegmentId + '\'' +

indexing-service/src/main/java/org/apache/druid/indexing/overlord/TaskLockbox.java

@@ -534,7 +534,7 @@ public class TaskLockbox
         request.getSequenceName(),
         request.getPrevisousSegmentId(),
         request.getInterval(),
-        request.getShardSpecFactory(),
+        request.getPartialShardSpec(),
         version,
         request.isSkipSegmentLineageCheck()
     );

indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/SeekableStreamIndexTask.java

@@ -54,7 +54,7 @@ import org.apache.druid.segment.realtime.appenderator.StreamAppenderatorDriver;
 import org.apache.druid.segment.realtime.firehose.ChatHandler;
 import org.apache.druid.segment.realtime.firehose.ChatHandlerProvider;
 import org.apache.druid.server.security.AuthorizerMapper;
-import org.apache.druid.timeline.partition.NumberedShardSpecFactory;
+import org.apache.druid.timeline.partition.NumberedPartialShardSpec;
 import org.apache.druid.utils.CircularBuffer;
 
 import javax.annotation.Nullable;
@@ -232,7 +232,7 @@ public abstract class SeekableStreamIndexTask<PartitionIdType, SequenceOffsetTyp
                 sequenceName,
                 previousSegmentId,
                 skipSegmentLineageCheck,
-                NumberedShardSpecFactory.instance(),
+                NumberedPartialShardSpec.instance(),
                 lockGranularityToUse
             )
         ),

indexing-service/src/test/java/org/apache/druid/indexing/common/actions/SegmentAllocateActionSerdeTest.java

@@ -0,0 +1,102 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.common.actions;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.collect.ImmutableMap;
+import org.apache.druid.indexing.common.LockGranularity;
+import org.apache.druid.jackson.DefaultObjectMapper;
+import org.apache.druid.java.util.common.DateTimes;
+import org.apache.druid.java.util.common.granularity.Granularities;
+import org.apache.druid.java.util.common.granularity.Granularity;
+import org.apache.druid.timeline.partition.NumberedPartialShardSpec;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.util.Map;
+
+public class SegmentAllocateActionSerdeTest
+{
+  private final ObjectMapper objectMapper;
+  private final SegmentAllocateAction target;
+
+  public SegmentAllocateActionSerdeTest()
+  {
+    objectMapper = new DefaultObjectMapper();
+    objectMapper.registerSubtypes(NumberedPartialShardSpec.class);
+
+    target = new SegmentAllocateAction(
+        "datasource",
+        DateTimes.nowUtc(),
+        Granularities.MINUTE,
+        Granularities.HOUR,
+        "s1",
+        "prev",
+        false,
+        NumberedPartialShardSpec.instance(),
+        LockGranularity.SEGMENT
+    );
+  }
+
+  @Test
+  public void testSerde() throws Exception
+  {
+    final SegmentAllocateAction fromJson = (SegmentAllocateAction) objectMapper.readValue(
+        objectMapper.writeValueAsBytes(target),
+        TaskAction.class
+    );
+
+    Assert.assertEquals(target.getDataSource(), fromJson.getDataSource());
+    Assert.assertEquals(target.getTimestamp(), fromJson.getTimestamp());
+    Assert.assertEquals(target.getQueryGranularity(), fromJson.getQueryGranularity());
+    Assert.assertEquals(target.getPreferredSegmentGranularity(), fromJson.getPreferredSegmentGranularity());
+    Assert.assertEquals(target.getSequenceName(), fromJson.getSequenceName());
+    Assert.assertEquals(target.getPreviousSegmentId(), fromJson.getPreviousSegmentId());
+    Assert.assertEquals(target.isSkipSegmentLineageCheck(), fromJson.isSkipSegmentLineageCheck());
+  }
+
+  @Test
+  public void testJsonPropertyNames() throws IOException
+  {
+    final Map<String, Object> fromJson = objectMapper.readValue(
+        objectMapper.writeValueAsBytes(target),
+        Map.class
+    );
+
+    Assert.assertEquals(10, fromJson.size());
+    Assert.assertEquals(SegmentAllocateAction.TYPE, fromJson.get("type"));
+    Assert.assertEquals(target.getDataSource(), fromJson.get("dataSource"));
+    Assert.assertEquals(target.getTimestamp(), DateTimes.of((String) fromJson.get("timestamp")));
+    Assert.assertEquals(
+        target.getQueryGranularity(),
+        Granularity.fromString((String) fromJson.get("queryGranularity"))
+    );
+    Assert.assertEquals(
+        target.getPreferredSegmentGranularity(),
+        Granularity.fromString((String) fromJson.get("preferredSegmentGranularity"))
+    );
+    Assert.assertEquals(target.getSequenceName(), fromJson.get("sequenceName"));
+    Assert.assertEquals(target.getPreviousSegmentId(), fromJson.get("previousSegmentId"));
+    Assert.assertEquals(target.isSkipSegmentLineageCheck(), fromJson.get("skipSegmentLineageCheck"));
+    Assert.assertEquals(ImmutableMap.of("type", "numbered"), fromJson.get("shardSpecFactory"));
+    Assert.assertEquals(target.getLockGranularity(), LockGranularity.valueOf((String) fromJson.get("lockGranularity")));
+  }
+}

indexing-service/src/test/java/org/apache/druid/indexing/common/actions/SegmentAllocateActionTest.java

@@ -38,14 +38,14 @@ import org.apache.druid.java.util.emitter.EmittingLogger;
 import org.apache.druid.java.util.emitter.service.ServiceEmitter;
 import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
 import org.apache.druid.timeline.DataSegment;
+import org.apache.druid.timeline.partition.HashBasedNumberedPartialShardSpec;
 import org.apache.druid.timeline.partition.HashBasedNumberedShardSpec;
-import org.apache.druid.timeline.partition.HashBasedNumberedShardSpecFactory;
+import org.apache.druid.timeline.partition.LinearPartialShardSpec;
 import org.apache.druid.timeline.partition.LinearShardSpec;
-import org.apache.druid.timeline.partition.LinearShardSpecFactory;
+import org.apache.druid.timeline.partition.NumberedPartialShardSpec;
 import org.apache.druid.timeline.partition.NumberedShardSpec;
-import org.apache.druid.timeline.partition.NumberedShardSpecFactory;
+import org.apache.druid.timeline.partition.PartialShardSpec;
 import org.apache.druid.timeline.partition.ShardSpec;
-import org.apache.druid.timeline.partition.ShardSpecFactory;
 import org.apache.druid.timeline.partition.SingleDimensionShardSpec;
 import org.easymock.EasyMock;
 import org.joda.time.DateTime;
@@ -652,7 +652,7 @@ public class SegmentAllocateActionTest
         Granularities.HOUR,
         "s1",
         null,
-        LinearShardSpecFactory.instance()
+        LinearPartialShardSpec.instance()
     );
     final SegmentIdWithShardSpec id2 = allocate(
         task,
@@ -661,7 +661,7 @@ public class SegmentAllocateActionTest
         Granularities.HOUR,
         "s1",
         id1.toString(),
-        LinearShardSpecFactory.instance()
+        LinearPartialShardSpec.instance()
     );
 
     assertSameIdentifier(
@@ -899,39 +899,7 @@ public class SegmentAllocateActionTest
   }
 
   @Test
-  public void testSerde() throws Exception
+  public void testWithPartialShardSpecAndOvershadowingSegments() throws IOException
-  {
-    final ObjectMapper objectMapper = new DefaultObjectMapper();
-    objectMapper.registerSubtypes(NumberedShardSpecFactory.class);
-
-    final SegmentAllocateAction action = new SegmentAllocateAction(
-        DATA_SOURCE,
-        PARTY_TIME,
-        Granularities.MINUTE,
-        Granularities.HOUR,
-        "s1",
-        "prev",
-        false,
-        NumberedShardSpecFactory.instance(),
-        lockGranularity
-    );
-
-    final SegmentAllocateAction action2 = (SegmentAllocateAction) objectMapper.readValue(
-        objectMapper.writeValueAsBytes(action),
-        TaskAction.class
-    );
-
-    Assert.assertEquals(action.getDataSource(), action2.getDataSource());
-    Assert.assertEquals(action.getTimestamp(), action2.getTimestamp());
-    Assert.assertEquals(action.getQueryGranularity(), action2.getQueryGranularity());
-    Assert.assertEquals(action.getPreferredSegmentGranularity(), action2.getPreferredSegmentGranularity());
-    Assert.assertEquals(action.getSequenceName(), action2.getSequenceName());
-    Assert.assertEquals(action.getPreviousSegmentId(), action2.getPreviousSegmentId());
-    Assert.assertEquals(action.isSkipSegmentLineageCheck(), action2.isSkipSegmentLineageCheck());
-  }
-
-  @Test
-  public void testWithShardSpecFactoryAndOvershadowingSegments() throws IOException
   {
     final Task task = NoopTask.create();
     taskActionTestKit.getTaskLockbox().add(task);
@@ -965,7 +933,7 @@ public class SegmentAllocateActionTest
         "seq",
         null,
         true,
-        new HashBasedNumberedShardSpecFactory(ImmutableList.of("dim1"), 2),
+        new HashBasedNumberedPartialShardSpec(ImmutableList.of("dim1"), 2),
         lockGranularity
     );
     final SegmentIdWithShardSpec segmentIdentifier = action.perform(task, taskActionTestKit.getTaskActionToolbox());
@@ -996,7 +964,7 @@ public class SegmentAllocateActionTest
         preferredSegmentGranularity,
         sequenceName,
         sequencePreviousId,
-        NumberedShardSpecFactory.instance()
+        NumberedPartialShardSpec.instance()
     );
   }
 
@@ -1007,7 +975,7 @@ public class SegmentAllocateActionTest
       final Granularity preferredSegmentGranularity,
       final String sequenceName,
       final String sequencePreviousId,
-      final ShardSpecFactory shardSpecFactory
+      final PartialShardSpec partialShardSpec
   )
   {
     final SegmentAllocateAction action = new SegmentAllocateAction(
@@ -1018,7 +986,7 @@ public class SegmentAllocateActionTest
         sequenceName,
         sequencePreviousId,
         false,
-        shardSpecFactory,
+        partialShardSpec,
         lockGranularity
     );
     return action.perform(task, taskActionTestKit.getTaskActionToolbox());

indexing-service/src/test/java/org/apache/druid/indexing/common/task/CompactionTaskParallelRunTest.java

@@ -236,7 +236,7 @@ public class CompactionTaskParallelRunTest extends AbstractParallelIndexSupervis
                 Granularities.MINUTE,
                 null
             ),
-            IndexTaskTest.createTuningConfig(2, 2, null, 2L, null, null, false, true),
+            IndexTaskTest.createTuningConfig(2, 2, null, 2L, null, false, true),
             false
         ),
         null,

indexing-service/src/test/java/org/apache/druid/indexing/common/task/CompactionTaskRunTest.java

@@ -386,7 +386,7 @@ public class CompactionTaskRunTest extends IngestionTestBase
                 Granularities.MINUTE,
                 null
             ),
-            IndexTaskTest.createTuningConfig(2, 2, null, 2L, null, null, false, true),
+            IndexTaskTest.createTuningConfig(2, 2, null, 2L, null, false, true),
             false
         ),
         null,
@@ -726,7 +726,7 @@ public class CompactionTaskRunTest extends IngestionTestBase
                 ),
                 false
             ),
-            IndexTaskTest.createTuningConfig(5000000, null, null, Long.MAX_VALUE, null, null, false, true)
+            IndexTaskTest.createTuningConfig(5000000, null, null, Long.MAX_VALUE, null, false, true)
         ),
         null,
         AuthTestUtils.TEST_AUTHORIZER_MAPPER,
@@ -796,7 +796,7 @@ public class CompactionTaskRunTest extends IngestionTestBase
                 Granularities.MINUTE,
                 null
             ),
-            IndexTaskTest.createTuningConfig(2, 2, null, 2L, null, null, false, true),
+            IndexTaskTest.createTuningConfig(2, 2, null, 2L, null, false, true),
             appendToExisting
         ),
         null,

indexing-service/src/test/java/org/apache/druid/indexing/common/task/CountingLocalTaskActionClientForTest.java

@@ -0,0 +1,68 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.common.task;
+
+import org.apache.druid.indexing.common.actions.LocalTaskActionClient;
+import org.apache.druid.indexing.common.actions.SurrogateAction;
+import org.apache.druid.indexing.common.actions.TaskAction;
+import org.apache.druid.indexing.common.actions.TaskActionClient;
+import org.apache.druid.indexing.common.actions.TaskActionToolbox;
+import org.apache.druid.indexing.common.actions.TaskAuditLogConfig;
+import org.apache.druid.indexing.overlord.TaskStorage;
+
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class CountingLocalTaskActionClientForTest implements TaskActionClient
+{
+  private final ConcurrentHashMap<Class<? extends TaskAction>, AtomicInteger> actionCountMap =
+      new ConcurrentHashMap<>();
+  private final LocalTaskActionClient delegate;
+
+  public CountingLocalTaskActionClientForTest(
+      Task task,
+      TaskStorage storage,
+      TaskActionToolbox toolbox
+  )
+  {
+    delegate = new LocalTaskActionClient(task, storage, toolbox, new TaskAuditLogConfig(false));
+  }
+
+  @Override
+  public <RetType> RetType submit(TaskAction<RetType> taskAction)
+  {
+    final RetType result = delegate.submit(taskAction);
+    final TaskAction actionKey;
+    if (taskAction instanceof SurrogateAction) {
+      actionKey = ((SurrogateAction) taskAction).getTaskAction();
+    } else {
+      actionKey = taskAction;
+    }
+    actionCountMap.computeIfAbsent(actionKey.getClass(), k -> new AtomicInteger()).incrementAndGet();
+    return result;
+  }
+
+  public int getActionCount(Class<? extends TaskAction> actionClass)
+  {
+    final AtomicInteger count = actionCountMap.get(actionClass);
+
+    return count == null ? 0 : count.get();
+  }
+}

indexing-service/src/test/java/org/apache/druid/indexing/common/task/IndexTaskTest.java

@@ -41,6 +41,8 @@ import org.apache.druid.indexer.TaskState;
 import org.apache.druid.indexer.TaskStatus;
 import org.apache.druid.indexer.partitions.DynamicPartitionsSpec;
 import org.apache.druid.indexer.partitions.HashedPartitionsSpec;
+import org.apache.druid.indexer.partitions.PartitionsSpec;
+import org.apache.druid.indexer.partitions.SingleDimensionPartitionsSpec;
 import org.apache.druid.indexing.common.IngestionStatsAndErrorsTaskReportData;
 import org.apache.druid.indexing.common.LockGranularity;
 import org.apache.druid.indexing.common.TaskReport;
@@ -459,7 +461,7 @@ public class IndexTaskTest extends IngestionTestBase
             null,
             null,
             null,
-            createTuningConfigWithNumShards(1, null, true),
+            createTuningConfigWithPartitionsSpec(new HashedPartitionsSpec(null, 1, null), true),
             false
         ),
         null,
@@ -501,7 +503,7 @@ public class IndexTaskTest extends IngestionTestBase
             null,
             null,
             null,
-            createTuningConfigWithNumShards(2, ImmutableList.of("dim"), true),
+            createTuningConfigWithPartitionsSpec(new HashedPartitionsSpec(null, 2, ImmutableList.of("dim")), true),
             false
         ),
         null,
@@ -558,7 +560,7 @@ public class IndexTaskTest extends IngestionTestBase
   }
 
   @Test
-  public void testAppendToExisting() throws Exception
+  public void testWriteNewSegmentsWithAppendToExistingWithLinearPartitioningSuccessfullyAppend() throws Exception
   {
     File tmpDir = temporaryFolder.newFolder();
     File tmpFile = File.createTempFile("druid", "index", tmpDir);
@@ -787,7 +789,7 @@ public class IndexTaskTest extends IngestionTestBase
                 Granularities.MINUTE,
                 null
             ),
-            createTuningConfig(2, 2, null, 2L, null, null, false, true),
+            createTuningConfig(2, 2, null, 2L, null, false, true),
             false
         ),
         null,
@@ -835,7 +837,7 @@ public class IndexTaskTest extends IngestionTestBase
                 true,
                 null
             ),
-            createTuningConfig(3, 2, null, 2L, null, null, true, true),
+            createTuningConfig(3, 2, null, 2L, null, true, true),
             false
         ),
         null,
@@ -882,7 +884,7 @@ public class IndexTaskTest extends IngestionTestBase
                 true,
                 null
             ),
-            createTuningConfig(3, 2, null, 2L, null, null, false, true),
+            createTuningConfig(3, 2, null, 2L, null, false, true),
             false
         ),
         null,
@@ -950,7 +952,7 @@ public class IndexTaskTest extends IngestionTestBase
             0
         ),
         null,
-        createTuningConfig(2, null, null, null, null, null, false, false), // ignore parse exception,
+        createTuningConfig(2, null, null, null, null, false, false), // ignore parse exception,
         false
     );
 
@@ -998,7 +1000,7 @@ public class IndexTaskTest extends IngestionTestBase
             0
         ),
         null,
-        createTuningConfig(2, null, null, null, null, null, false, true), // report parse exception
+        createTuningConfig(2, null, null, null, null, false, true), // report parse exception
         false
     );
 
@@ -1418,7 +1420,7 @@ public class IndexTaskTest extends IngestionTestBase
             0
         ),
         null,
-        createTuningConfig(2, 1, null, null, null, null, true, true), // report parse exception
+        createTuningConfig(2, 1, null, null, null, true, true), // report parse exception
         false
     );
 
@@ -1483,7 +1485,7 @@ public class IndexTaskTest extends IngestionTestBase
             0
         ),
         null,
-        createTuningConfig(2, null, null, null, null, null, false, true), // report parse exception
+        createTuningConfig(2, null, null, null, null, false, true), // report parse exception
         false
     );
 
@@ -1538,7 +1540,7 @@ public class IndexTaskTest extends IngestionTestBase
                   true,
                   null
               ),
-              createTuningConfig(3, 2, null, 2L, null, null, false, true),
+              createTuningConfig(3, 2, null, 2L, null, false, true),
               false
           ),
           null,
@@ -1607,7 +1609,7 @@ public class IndexTaskTest extends IngestionTestBase
                   true,
                   null
               ),
-              createTuningConfig(3, 2, null, 2L, null, null, false, true),
+              createTuningConfig(3, 2, null, 2L, null, false, true),
               false
           ),
           null,
@@ -1634,6 +1636,35 @@ public class IndexTaskTest extends IngestionTestBase
     }
   }
 
+  @Test
+  public void testIndexTaskWitSingleDimPartitionsSpecThrowingException() throws Exception
+  {
+    final IndexTask task = new IndexTask(
+        null,
+        null,
+        createIngestionSpec(
+            useInputFormatApi,
+            jsonMapper,
+            null,
+            null,
+            null,
+            null,
+            createTuningConfigWithPartitionsSpec(new SingleDimensionPartitionsSpec(null, 1, null, false), true),
+            false
+        ),
+        null,
+        AuthTestUtils.TEST_AUTHORIZER_MAPPER,
+        null,
+        rowIngestionMetersFactory,
+        appenderatorsManager
+    );
+    expectedException.expect(UnsupportedOperationException.class);
+    expectedException.expectMessage(
+        "partitionsSpec[org.apache.druid.indexer.partitions.SingleDimensionPartitionsSpec] is not supported"
+    );
+    task.isReady(createActionClient(task));
+  }
+
   public static void checkTaskStatusErrorMsgForParseExceptionsExceeded(TaskStatus status)
   {
     // full stacktrace will be too long and make tests brittle (e.g. if line # changes), just match the main message
@@ -1662,15 +1693,13 @@ public class IndexTaskTest extends IngestionTestBase
         null,
         null,
         null,
-        null,
         forceGuaranteedRollup,
         true
     );
   }
 
-  private static IndexTuningConfig createTuningConfigWithNumShards(
+  private static IndexTuningConfig createTuningConfigWithPartitionsSpec(
-      int numShards,
+      PartitionsSpec partitionsSpec,
-      @Nullable List<String> partitionDimensions,
       boolean forceGuaranteedRollup
   )
   {
@@ -1679,8 +1708,7 @@ public class IndexTaskTest extends IngestionTestBase
         1,
         null,
         null,
-        numShards,
+        partitionsSpec,
-        partitionDimensions,
         forceGuaranteedRollup,
         true
     );
@@ -1691,8 +1719,7 @@ public class IndexTaskTest extends IngestionTestBase
       @Nullable Integer maxRowsInMemory,
       @Nullable Long maxBytesInMemory,
       @Nullable Long maxTotalRows,
-      @Nullable Integer numShards,
+      @Nullable PartitionsSpec partitionsSpec,
-      @Nullable List<String> partitionDimensions,
       boolean forceGuaranteedRollup,
       boolean reportParseException
   )
@@ -1704,9 +1731,9 @@ public class IndexTaskTest extends IngestionTestBase
         maxBytesInMemory,
         maxTotalRows,
         null,
-        numShards,
-        partitionDimensions,
         null,
+        null,
+        partitionsSpec,
         INDEX_SPEC,
         null,
         null,

indexing-service/src/test/java/org/apache/druid/indexing/common/task/IngestionTestBase.java

@@ -28,12 +28,10 @@ import org.apache.druid.indexing.common.SegmentLoaderFactory;
 import org.apache.druid.indexing.common.SingleFileTaskReportFileWriter;
 import org.apache.druid.indexing.common.TaskToolbox;
 import org.apache.druid.indexing.common.TestUtils;
-import org.apache.druid.indexing.common.actions.LocalTaskActionClient;
 import org.apache.druid.indexing.common.actions.SegmentInsertAction;
 import org.apache.druid.indexing.common.actions.SegmentTransactionalInsertAction;
 import org.apache.druid.indexing.common.actions.TaskAction;
 import org.apache.druid.indexing.common.actions.TaskActionToolbox;
-import org.apache.druid.indexing.common.actions.TaskAuditLogConfig;
 import org.apache.druid.indexing.common.config.TaskStorageConfig;
 import org.apache.druid.indexing.common.stats.RowIngestionMetersFactory;
 import org.apache.druid.indexing.overlord.HeapMemoryTaskStorage;
@@ -209,13 +207,13 @@ public abstract class IngestionTestBase extends InitializedNullHandlingTest
     return testUtils.getTestIndexMergerV9();
   }
 
-  public class TestLocalTaskActionClient extends LocalTaskActionClient
+  public class TestLocalTaskActionClient extends CountingLocalTaskActionClientForTest
   {
     private final Set<DataSegment> publishedSegments = new HashSet<>();
 
     private TestLocalTaskActionClient(Task task)
     {
-      super(task, taskStorage, createTaskActionToolbox(), new TaskAuditLogConfig(false));
+      super(task, taskStorage, createTaskActionToolbox());
     }
 
     @Override

indexing-service/src/test/java/org/apache/druid/indexing/common/task/RangePartitionCachingLocalSegmentAllocatorTest.java

@@ -21,16 +21,18 @@ package org.apache.druid.indexing.common.task;
 
 import com.google.common.collect.ImmutableMap;
 import org.apache.druid.data.input.InputRow;
+import org.apache.druid.indexer.partitions.SingleDimensionPartitionsSpec;
 import org.apache.druid.indexing.common.TaskLock;
 import org.apache.druid.indexing.common.TaskToolbox;
 import org.apache.druid.indexing.common.actions.LockListAction;
 import org.apache.druid.indexing.common.actions.TaskActionClient;
-import org.apache.druid.indexing.common.task.batch.parallel.distribution.PartitionBoundaries;
+import org.apache.druid.indexing.common.task.batch.partition.RangePartitionAnalysis;
 import org.apache.druid.java.util.common.DateTimes;
 import org.apache.druid.java.util.common.Intervals;
 import org.apache.druid.java.util.common.StringUtils;
 import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
 import org.apache.druid.timeline.SegmentId;
+import org.apache.druid.timeline.partition.PartitionBoundaries;
 import org.apache.druid.timeline.partition.SingleDimensionShardSpec;
 import org.easymock.EasyMock;
 import org.joda.time.Interval;
@@ -79,7 +81,8 @@ public class RangePartitionCachingLocalSegmentAllocatorTest
       INTERVAL_NORMAL, NORMAL_PARTITIONS
   );
 
-  private RangePartitionCachingLocalSegmentAllocator target;
+  private CachingSegmentAllocator target;
+  private SequenceNameFunction sequenceNameFunction;
 
   @Rule
   public ExpectedException exception = ExpectedException.none();
@@ -93,14 +96,18 @@ public class RangePartitionCachingLocalSegmentAllocatorTest
                            .map(RangePartitionCachingLocalSegmentAllocatorTest::createTaskLock)
                            .collect(Collectors.toList())
     );
-    target = new RangePartitionCachingLocalSegmentAllocator(
+    final RangePartitionAnalysis partitionAnalysis = new RangePartitionAnalysis(
-        toolbox,
+        new SingleDimensionPartitionsSpec(null, 1, PARTITION_DIMENSION, false)
-        TASKID,
-        SUPERVISOR_TASKID,
-        DATASOURCE,
-        PARTITION_DIMENSION,
-        INTERVAL_TO_PARTITONS
     );
+    INTERVAL_TO_PARTITONS.forEach(partitionAnalysis::updateBucket);
+    target = SegmentAllocators.forNonLinearPartitioning(
+        toolbox,
+        DATASOURCE,
+        TASKID,
+        new SupervisorTaskAccessWithNullClient(SUPERVISOR_TASKID),
+        partitionAnalysis
+    );
+    sequenceNameFunction = new NonLinearlyPartitionedSequenceNameFunction(TASKID, target.getShardSpecs());
   }
 
   @Test
@@ -112,7 +119,7 @@ public class RangePartitionCachingLocalSegmentAllocatorTest
     exception.expect(IllegalStateException.class);
     exception.expectMessage("Failed to get shardSpec");
 
-    String sequenceName = target.getSequenceName(interval, row);
+    String sequenceName = sequenceNameFunction.getSequenceName(interval, row);
     allocate(row, sequenceName);
   }
 
@@ -148,7 +155,7 @@ public class RangePartitionCachingLocalSegmentAllocatorTest
     // getSequenceName_forIntervalAndRow_shouldUseISOFormatAndPartitionNumForRow
     Interval interval = INTERVAL_NORMAL;
     InputRow row = createInputRow(interval, PARTITION9);
-    String sequenceName = target.getSequenceName(interval, row);
+    String sequenceName = sequenceNameFunction.getSequenceName(interval, row);
     String expectedSequenceName = StringUtils.format("%s_%s_%d", TASKID, interval, 1);
     Assert.assertEquals(expectedSequenceName, sequenceName);
   }
@@ -189,7 +196,7 @@ public class RangePartitionCachingLocalSegmentAllocatorTest
       @Nullable String partitionEnd
   )
   {
-    String sequenceName = target.getSequenceName(interval, row);
+    String sequenceName = sequenceNameFunction.getSequenceName(interval, row);
     SegmentIdWithShardSpec segmentIdWithShardSpec = allocate(row, sequenceName);
 
     Assert.assertEquals(
@@ -209,7 +216,7 @@ public class RangePartitionCachingLocalSegmentAllocatorTest
       return target.allocate(row, sequenceName, null, false);
     }
     catch (IOException e) {
-      throw new UncheckedIOException(e);
+      throw new RuntimeException(e);
     }
   }
 

indexing-service/src/test/java/org/apache/druid/indexing/common/task/SupervisorTaskAccessWithNullClient.java

@@ -0,0 +1,30 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.indexing.common.task;
+
+import org.apache.druid.indexing.common.task.batch.parallel.SupervisorTaskAccess;
+
+public class SupervisorTaskAccessWithNullClient extends SupervisorTaskAccess
+{
+  public SupervisorTaskAccessWithNullClient(String supervisorTaskId)
+  {
+    super(supervisorTaskId, null);
+  }
+}

indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/HashPartitionCachingLocalSegmentAllocatorTest.java

@@ -23,20 +23,23 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import org.apache.druid.data.input.InputRow;
+import org.apache.druid.data.input.MapBasedInputRow;
+import org.apache.druid.indexer.partitions.HashedPartitionsSpec;
 import org.apache.druid.indexing.common.TaskLock;
 import org.apache.druid.indexing.common.TaskToolbox;
 import org.apache.druid.indexing.common.actions.LockListAction;
 import org.apache.druid.indexing.common.actions.TaskActionClient;
-import org.apache.druid.indexing.common.task.HashPartitionCachingLocalSegmentAllocator;
+import org.apache.druid.indexing.common.task.CachingSegmentAllocator;
-import org.apache.druid.java.util.common.DateTimes;
+import org.apache.druid.indexing.common.task.NonLinearlyPartitionedSequenceNameFunction;
+import org.apache.druid.indexing.common.task.SegmentAllocators;
+import org.apache.druid.indexing.common.task.SequenceNameFunction;
+import org.apache.druid.indexing.common.task.SupervisorTaskAccessWithNullClient;
+import org.apache.druid.indexing.common.task.batch.partition.HashPartitionAnalysis;
 import org.apache.druid.java.util.common.Intervals;
-import org.apache.druid.java.util.common.Pair;
 import org.apache.druid.java.util.common.StringUtils;
 import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
 import org.apache.druid.timeline.SegmentId;
 import org.apache.druid.timeline.partition.HashBasedNumberedShardSpec;
-import org.apache.druid.timeline.partition.HashBasedNumberedShardSpecFactory;
-import org.apache.druid.timeline.partition.ShardSpecFactory;
 import org.easymock.EasyMock;
 import org.joda.time.Interval;
 import org.junit.Assert;
@@ -47,7 +50,6 @@ import java.io.IOException;
 import java.io.UncheckedIOException;
 import java.util.Collections;
 import java.util.List;
-import java.util.Map;
 
 public class HashPartitionCachingLocalSegmentAllocatorTest
 {
@@ -60,28 +62,30 @@ public class HashPartitionCachingLocalSegmentAllocatorTest
   private static final String DIMENSION = "dim";
   private static final List<String> PARTITION_DIMENSIONS = ImmutableList.of(DIMENSION);
   private static final int NUM_PARTITONS = 1;
-  private static final ShardSpecFactory SHARD_SPEC_FACTORY = new HashBasedNumberedShardSpecFactory(
-      PARTITION_DIMENSIONS,
-      NUM_PARTITONS
-  );
   private static final int PARTITION_NUM = 0;
-  private static final Map<Interval, Pair<ShardSpecFactory, Integer>> ALLOCATE_SPEC = ImmutableMap.of(
+  private static final HashedPartitionsSpec PARTITIONS_SPEC = new HashedPartitionsSpec(
-      INTERVAL, Pair.of(SHARD_SPEC_FACTORY, NUM_PARTITONS)
+      null,
+      null,
+      Collections.singletonList(DIMENSION)
   );
 
-  private HashPartitionCachingLocalSegmentAllocator target;
+  private CachingSegmentAllocator target;
+  private SequenceNameFunction sequenceNameFunction;
 
   @Before
   public void setup() throws IOException
   {
     TaskToolbox toolbox = createToolbox();
-    target = new HashPartitionCachingLocalSegmentAllocator(
+    HashPartitionAnalysis partitionAnalysis = new HashPartitionAnalysis(PARTITIONS_SPEC);
+    partitionAnalysis.updateBucket(INTERVAL, NUM_PARTITONS);
+    target = SegmentAllocators.forNonLinearPartitioning(
         toolbox,
-        TASKID,
-        SUPERVISOR_TASKID,
         DATASOURCE,
-        ALLOCATE_SPEC
+        TASKID,
+        new SupervisorTaskAccessWithNullClient(SUPERVISOR_TASKID),
+        partitionAnalysis
     );
+    sequenceNameFunction = new NonLinearlyPartitionedSequenceNameFunction(TASKID, target.getShardSpecs());
   }
 
   @Test
@@ -89,7 +93,7 @@ public class HashPartitionCachingLocalSegmentAllocatorTest
   {
     InputRow row = createInputRow();
 
-    String sequenceName = target.getSequenceName(INTERVAL, row);
+    String sequenceName = sequenceNameFunction.getSequenceName(INTERVAL, row);
     SegmentIdWithShardSpec segmentIdWithShardSpec = target.allocate(row, sequenceName, null, false);
 
     Assert.assertEquals(
@@ -102,13 +106,12 @@ public class HashPartitionCachingLocalSegmentAllocatorTest
     Assert.assertEquals(PARTITION_NUM, shardSpec.getPartitionNum());
   }
 
-
   @Test
   public void getSequenceName()
   {
     // getSequenceName_forIntervalAndRow_shouldUseISOFormatAndPartitionNumForRow
     InputRow row = createInputRow();
-    String sequenceName = target.getSequenceName(INTERVAL, row);
+    String sequenceName = sequenceNameFunction.getSequenceName(INTERVAL, row);
     String expectedSequenceName = StringUtils.format("%s_%s_%d", TASKID, INTERVAL, PARTITION_NUM);
     Assert.assertEquals(expectedSequenceName, sequenceName);
   }
@@ -148,12 +151,11 @@ public class HashPartitionCachingLocalSegmentAllocatorTest
 
   private static InputRow createInputRow()
   {
-    long timestamp = INTERVAL.getStartMillis();
+    final long timestamp = INTERVAL.getStartMillis();
-    InputRow inputRow = EasyMock.mock(InputRow.class);
+    return new MapBasedInputRow(
-    EasyMock.expect(inputRow.getTimestamp()).andStubReturn(DateTimes.utc(timestamp));
+        timestamp,
-    EasyMock.expect(inputRow.getTimestampFromEpoch()).andStubReturn(timestamp);
+        Collections.singletonList(DIMENSION),
-    EasyMock.expect(inputRow.getDimension(DIMENSION)).andStubReturn(Collections.singletonList(DIMENSION));
+        ImmutableMap.of(DIMENSION, 1)
-    EasyMock.replay(inputRow);
+    );
-    return inputRow;
   }
 }

indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/ParallelIndexSupervisorTaskResourceTest.java

@@ -34,9 +34,11 @@ import org.apache.druid.indexer.TaskLocation;
 import org.apache.druid.indexer.TaskState;
 import org.apache.druid.indexer.TaskStatus;
 import org.apache.druid.indexer.TaskStatusPlus;
+import org.apache.druid.indexer.partitions.DynamicPartitionsSpec;
 import org.apache.druid.indexing.common.TaskToolbox;
 import org.apache.druid.indexing.common.task.AbstractTask;
 import org.apache.druid.indexing.common.task.IndexTaskClientFactory;
+import org.apache.druid.indexing.common.task.SegmentAllocators;
 import org.apache.druid.indexing.common.task.TaskResource;
 import org.apache.druid.indexing.common.task.TestAppenderatorsManager;
 import org.apache.druid.indexing.common.task.batch.parallel.ParallelIndexTaskRunner.SubTaskSpecStatus;
@@ -685,8 +687,17 @@ public class ParallelIndexSupervisorTaskResourceTest extends AbstractParallelInd
 
       // build LocalParallelIndexTaskClient
       final ParallelIndexSupervisorTaskClient taskClient = taskClientFactory.build(null, getId(), 0, null, 0);
-
+      final DynamicPartitionsSpec partitionsSpec = (DynamicPartitionsSpec) getIngestionSchema()
-      final SegmentAllocator segmentAllocator = createSegmentAllocator(toolbox, taskClient);
+          .getTuningConfig()
+          .getGivenOrDefaultPartitionsSpec();
+      final SegmentAllocator segmentAllocator = SegmentAllocators.forLinearPartitioning(
+          toolbox,
+          new SupervisorTaskAccess(getSupervisorTaskId(), taskClient),
+          getIngestionSchema().getDataSchema(),
+          getTaskLockHelper(),
+          getIngestionSchema().getIOConfig().isAppendToExisting(),
+          partitionsSpec
+      );
 
       final SegmentIdWithShardSpec segmentIdentifier = segmentAllocator.allocate(
           new MapBasedInputRow(DateTimes.of("2017-01-01"), Collections.emptyList(), Collections.emptyMap()),

indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/ParallelIndexSupervisorTaskSerdeTest.java

@@ -155,10 +155,8 @@ public class ParallelIndexSupervisorTaskSerdeTest
   @Test
   public void forceGuaranteedRollupWithSingleDimPartitionsMissingDimension()
   {
-    expectedException.expect(IllegalStateException.class);
+    expectedException.expect(IllegalArgumentException.class);
-    expectedException.expectMessage(
+    expectedException.expectMessage("partitionDimension must be specified");
-        "forceGuaranteedRollup is incompatible with partitionsSpec: partitionDimension must be specified"
-    );
 
     new ParallelIndexSupervisorTaskBuilder()
         .ingestionSpec(

indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/PartialDimensionDistributionTaskTest.java

@@ -33,13 +33,13 @@ import org.apache.druid.indexer.partitions.PartitionsSpec;
 import org.apache.druid.indexer.partitions.SingleDimensionPartitionsSpec;
 import org.apache.druid.indexing.common.TaskToolbox;
 import org.apache.druid.indexing.common.task.IndexTaskClientFactory;
-import org.apache.druid.indexing.common.task.batch.parallel.distribution.PartitionBoundaries;
 import org.apache.druid.indexing.common.task.batch.parallel.distribution.StringDistribution;
 import org.apache.druid.indexing.common.task.batch.parallel.distribution.StringSketch;
 import org.apache.druid.java.util.common.StringUtils;
 import org.apache.druid.segment.TestHelper;
 import org.apache.druid.segment.indexing.DataSchema;
 import org.apache.druid.testing.junit.LoggerCaptureRule;
+import org.apache.druid.timeline.partition.PartitionBoundaries;
 import org.apache.logging.log4j.core.LogEvent;
 import org.easymock.Capture;
 import org.easymock.EasyMock;

indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/PartialHashSegmentGenerateTaskTest.java

@@ -20,15 +20,23 @@
 package org.apache.druid.indexing.common.task.batch.parallel;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.collect.ImmutableList;
 import org.apache.druid.data.input.impl.JsonInputFormat;
 import org.apache.druid.data.input.impl.LocalInputSource;
+import org.apache.druid.indexer.partitions.HashedPartitionsSpec;
+import org.apache.druid.indexing.common.task.batch.partition.HashPartitionAnalysis;
+import org.apache.druid.java.util.common.Intervals;
+import org.apache.druid.java.util.common.granularity.Granularities;
 import org.apache.druid.segment.TestHelper;
+import org.apache.druid.segment.indexing.granularity.UniformGranularitySpec;
 import org.hamcrest.Matchers;
+import org.joda.time.Interval;
 import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
 import java.io.File;
+import java.util.List;
 
 public class PartialHashSegmentGenerateTaskTest
 {
@@ -71,4 +79,28 @@ public class PartialHashSegmentGenerateTaskTest
     String id = target.getId();
     Assert.assertThat(id, Matchers.startsWith(PartialHashSegmentGenerateTask.TYPE));
   }
+
+  @Test
+  public void testCreateHashPartitionAnalysisFromPartitionsSpecWithNumShardsReturningAnalysisOfValidNumBuckets()
+  {
+    final List<Interval> intervals = ImmutableList.of(
+        Intervals.of("2020-01-01/2020-01-02"),
+        Intervals.of("2020-01-02/2020-01-03"),
+        Intervals.of("2020-01-03/2020-01-04")
+    );
+    final int expectedNumBuckets = 5;
+    final HashPartitionAnalysis partitionAnalysis = PartialHashSegmentGenerateTask
+        .createHashPartitionAnalysisFromPartitionsSpec(
+            new UniformGranularitySpec(
+                Granularities.DAY,
+                Granularities.NONE,
+                intervals
+            ),
+            new HashedPartitionsSpec(null, expectedNumBuckets, null)
+        );
+    Assert.assertEquals(intervals.size(), partitionAnalysis.getNumTimePartitions());
+    for (Interval interval : intervals) {
+      Assert.assertEquals(expectedNumBuckets, partitionAnalysis.getBucketAnalysis(interval).intValue());
+    }
+  }
 }

indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/PartialRangeSegmentGenerateTaskTest.java

@@ -28,10 +28,10 @@ import org.apache.druid.indexer.partitions.DynamicPartitionsSpec;
 import org.apache.druid.indexer.partitions.HashedPartitionsSpec;
 import org.apache.druid.indexer.partitions.PartitionsSpec;
 import org.apache.druid.indexing.common.task.IndexTaskClientFactory;
-import org.apache.druid.indexing.common.task.batch.parallel.distribution.PartitionBoundaries;
 import org.apache.druid.java.util.common.Intervals;
 import org.apache.druid.segment.TestHelper;
 import org.apache.druid.segment.indexing.DataSchema;
+import org.apache.druid.timeline.partition.PartitionBoundaries;
 import org.hamcrest.Matchers;
 import org.junit.Assert;
 import org.junit.Rule;

indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/RangePartitionMultiPhaseParallelIndexingTest.java

@@ -36,13 +36,13 @@ import org.apache.druid.indexing.common.TaskToolbox;
 import org.apache.druid.indexing.common.task.IndexTaskClientFactory;
 import org.apache.druid.indexing.common.task.TaskResource;
 import org.apache.druid.indexing.common.task.TestAppenderatorsManager;
-import org.apache.druid.indexing.common.task.batch.parallel.distribution.PartitionBoundaries;
 import org.apache.druid.java.util.common.ISE;
 import org.apache.druid.java.util.common.Intervals;
 import org.apache.druid.java.util.common.StringUtils;
 import org.apache.druid.java.util.common.guava.Comparators;
 import org.apache.druid.query.scan.ScanResultValue;
 import org.apache.druid.timeline.DataSegment;
+import org.apache.druid.timeline.partition.PartitionBoundaries;
 import org.apache.druid.timeline.partition.SingleDimensionShardSpec;
 import org.hamcrest.Matchers;
 import org.joda.time.Interval;

indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/distribution/StringSketchMergerTest.java

@@ -19,6 +19,7 @@
 
 package org.apache.druid.indexing.common.task.batch.parallel.distribution;
 
+import org.apache.druid.timeline.partition.PartitionBoundaries;
 import org.easymock.EasyMock;
 import org.junit.Assert;
 import org.junit.Before;

indexing-service/src/test/java/org/apache/druid/indexing/common/task/batch/parallel/distribution/StringSketchTest.java

@@ -25,6 +25,7 @@ import org.apache.datasketches.quantiles.ItemsSketch;
 import org.apache.druid.jackson.JacksonModule;
 import org.apache.druid.java.util.common.StringUtils;
 import org.apache.druid.segment.TestHelper;
+import org.apache.druid.timeline.partition.PartitionBoundaries;
 import org.hamcrest.Matchers;
 import org.hamcrest.number.IsCloseTo;
 import org.junit.Assert;

indexing-service/src/test/java/org/apache/druid/indexing/overlord/TaskLockboxTest.java

@@ -54,13 +54,13 @@ import org.apache.druid.metadata.MetadataStorageTablesConfig;
 import org.apache.druid.metadata.TestDerbyConnector;
 import org.apache.druid.segment.TestHelper;
 import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
+import org.apache.druid.timeline.partition.HashBasedNumberedPartialShardSpec;
 import org.apache.druid.timeline.partition.HashBasedNumberedShardSpec;
-import org.apache.druid.timeline.partition.HashBasedNumberedShardSpecFactory;
+import org.apache.druid.timeline.partition.NumberedOverwritePartialShardSpec;
-import org.apache.druid.timeline.partition.NumberedOverwritingShardSpecFactory;
+import org.apache.druid.timeline.partition.NumberedPartialShardSpec;
 import org.apache.druid.timeline.partition.NumberedShardSpec;
-import org.apache.druid.timeline.partition.NumberedShardSpecFactory;
+import org.apache.druid.timeline.partition.PartialShardSpec;
 import org.apache.druid.timeline.partition.PartitionIds;
-import org.apache.druid.timeline.partition.ShardSpecFactory;
 import org.easymock.EasyMock;
 import org.joda.time.Interval;
 import org.junit.Assert;
@@ -949,8 +949,8 @@ public class TaskLockboxTest
   {
     final Task task = NoopTask.create();
     lockbox.add(task);
-    allocateSegmentsAndAssert(task, "seq", 3, NumberedShardSpecFactory.instance());
+    allocateSegmentsAndAssert(task, "seq", 3, NumberedPartialShardSpec.instance());
-    allocateSegmentsAndAssert(task, "seq2", 2, new NumberedOverwritingShardSpecFactory(0, 3, (short) 1));
+    allocateSegmentsAndAssert(task, "seq2", 2, new NumberedOverwritePartialShardSpec(0, 3, (short) 1));
 
     final List<TaskLock> locks = lockbox.findLocksForTask(task);
     Assert.assertEquals(5, locks.size());
@@ -971,15 +971,15 @@ public class TaskLockboxTest
     final Task task = NoopTask.create();
     lockbox.add(task);
 
-    allocateSegmentsAndAssert(task, "seq", 3, new HashBasedNumberedShardSpecFactory(null, 3));
+    allocateSegmentsAndAssert(task, "seq", 3, new HashBasedNumberedPartialShardSpec(null, 3));
-    allocateSegmentsAndAssert(task, "seq2", 5, new HashBasedNumberedShardSpecFactory(null, 5));
+    allocateSegmentsAndAssert(task, "seq2", 5, new HashBasedNumberedPartialShardSpec(null, 5));
   }
 
   private void allocateSegmentsAndAssert(
       Task task,
       String baseSequenceName,
       int numSegmentsToAllocate,
-      ShardSpecFactory shardSpecFactory
+      PartialShardSpec partialShardSpec
   )
   {
     for (int i = 0; i < numSegmentsToAllocate; i++) {
@@ -988,7 +988,7 @@ public class TaskLockboxTest
           TaskLockType.EXCLUSIVE,
           task,
           Intervals.of("2015-01-01/2015-01-05"),
-          shardSpecFactory,
+          partialShardSpec,
           StringUtils.format("%s_%d", baseSequenceName, i),
           null,
           true
@@ -1013,7 +1013,7 @@ public class TaskLockboxTest
     Assert.assertEquals(lockRequest.getGroupId(), segmentLock.getGroupId());
     Assert.assertEquals(lockRequest.getDataSource(), segmentLock.getDataSource());
     Assert.assertEquals(lockRequest.getInterval(), segmentLock.getInterval());
-    Assert.assertEquals(lockRequest.getShardSpecFactory().getShardSpecClass(), segmentId.getShardSpec().getClass());
+    Assert.assertEquals(lockRequest.getPartialShardSpec().getShardSpecClass(), segmentId.getShardSpec().getClass());
     Assert.assertEquals(lockRequest.getPriority(), lockRequest.getPriority());
   }
 

indexing-service/src/test/java/org/apache/druid/indexing/test/TestIndexerMetadataStorageCoordinator.java

@@ -31,7 +31,7 @@ import org.apache.druid.jackson.DefaultObjectMapper;
 import org.apache.druid.java.util.common.Pair;
 import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
 import org.apache.druid.timeline.DataSegment;
-import org.apache.druid.timeline.partition.ShardSpecFactory;
+import org.apache.druid.timeline.partition.PartialShardSpec;
 import org.joda.time.Interval;
 
 import java.util.ArrayList;
@@ -144,7 +144,7 @@ public class TestIndexerMetadataStorageCoordinator implements IndexerMetadataSto
       String sequenceName,
       String previousSegmentId,
       Interval interval,
-      ShardSpecFactory shardSpecFactory,
+      PartialShardSpec partialShardSpec,
       String maxVersion,
       boolean skipSegmentLineageCheck
   )
@@ -153,7 +153,7 @@ public class TestIndexerMetadataStorageCoordinator implements IndexerMetadataSto
         dataSource,
         interval,
         maxVersion,
-        shardSpecFactory.create(objectMapper, 0)
+        partialShardSpec.complete(objectMapper, 0)
     );
   }
 

server/src/main/java/org/apache/druid/indexing/overlord/IndexerMetadataStorageCoordinator.java

@@ -22,7 +22,7 @@ package org.apache.druid.indexing.overlord;
 import org.apache.druid.java.util.common.Pair;
 import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
 import org.apache.druid.timeline.DataSegment;
-import org.apache.druid.timeline.partition.ShardSpecFactory;
+import org.apache.druid.timeline.partition.PartialShardSpec;
 import org.joda.time.Interval;
 
 import javax.annotation.Nullable;
@@ -157,7 +157,7 @@ public interface IndexerMetadataStorageCoordinator
    * @param previousSegmentId       previous segment in the series; may be null or empty, meaning this is the first
    *                                segment
    * @param interval                interval for which to allocate a segment
-   * @param shardSpecFactory        shardSpecFactory containing all necessary information to create a shardSpec for the
+   * @param partialShardSpec        partialShardSpec containing all necessary information to create a shardSpec for the
    *                                new segmentId
    * @param maxVersion              use this version if we have no better version to use. The returned segment
    *                                identifier may have a version lower than this one, but will not have one higher.
@@ -171,7 +171,7 @@ public interface IndexerMetadataStorageCoordinator
       String sequenceName,
       @Nullable String previousSegmentId,
       Interval interval,
-      ShardSpecFactory shardSpecFactory,
+      PartialShardSpec partialShardSpec,
       String maxVersion,
       boolean skipSegmentLineageCheck
   );

server/src/main/java/org/apache/druid/metadata/IndexerSQLMetadataStorageCoordinator.java

@@ -48,9 +48,9 @@ import org.apache.druid.timeline.Partitions;
 import org.apache.druid.timeline.TimelineObjectHolder;
 import org.apache.druid.timeline.VersionedIntervalTimeline;
 import org.apache.druid.timeline.partition.NoneShardSpec;
+import org.apache.druid.timeline.partition.PartialShardSpec;
 import org.apache.druid.timeline.partition.PartitionChunk;
 import org.apache.druid.timeline.partition.ShardSpec;
-import org.apache.druid.timeline.partition.ShardSpecFactory;
 import org.joda.time.Interval;
 import org.skife.jdbi.v2.Folder3;
 import org.skife.jdbi.v2.Handle;
@@ -494,7 +494,7 @@ public class IndexerSQLMetadataStorageCoordinator implements IndexerMetadataStor
       final String sequenceName,
       @Nullable final String previousSegmentId,
       final Interval interval,
-      final ShardSpecFactory shardSpecFactory,
+      final PartialShardSpec partialShardSpec,
       final String maxVersion,
       final boolean skipSegmentLineageCheck
   )
@@ -512,7 +512,7 @@ public class IndexerSQLMetadataStorageCoordinator implements IndexerMetadataStor
                 dataSource,
                 sequenceName,
                 interval,
-                shardSpecFactory,
+                partialShardSpec,
                 maxVersion
             );
           } else {
@@ -522,7 +522,7 @@ public class IndexerSQLMetadataStorageCoordinator implements IndexerMetadataStor
                 sequenceName,
                 previousSegmentId,
                 interval,
-                shardSpecFactory,
+                partialShardSpec,
                 maxVersion
             );
           }
@@ -537,7 +537,7 @@ public class IndexerSQLMetadataStorageCoordinator implements IndexerMetadataStor
       final String sequenceName,
       @Nullable final String previousSegmentId,
       final Interval interval,
-      final ShardSpecFactory shardSpecFactory,
+      final PartialShardSpec partialShardSpec,
       final String maxVersion
   ) throws IOException
   {
@@ -569,7 +569,7 @@ public class IndexerSQLMetadataStorageCoordinator implements IndexerMetadataStor
         handle,
         dataSource,
         interval,
-        shardSpecFactory,
+        partialShardSpec,
         maxVersion
     );
     if (newIdentifier == null) {
@@ -611,7 +611,7 @@ public class IndexerSQLMetadataStorageCoordinator implements IndexerMetadataStor
       final String dataSource,
       final String sequenceName,
       final Interval interval,
-      final ShardSpecFactory shardSpecFactory,
+      final PartialShardSpec partialShardSpec,
       final String maxVersion
   ) throws IOException
   {
@@ -645,7 +645,7 @@ public class IndexerSQLMetadataStorageCoordinator implements IndexerMetadataStor
         handle,
         dataSource,
         interval,
-        shardSpecFactory,
+        partialShardSpec,
         maxVersion
     );
     if (newIdentifier == null) {
@@ -788,7 +788,7 @@ public class IndexerSQLMetadataStorageCoordinator implements IndexerMetadataStor
       final Handle handle,
       final String dataSource,
       final Interval interval,
-      final ShardSpecFactory shardSpecFactory,
+      final PartialShardSpec partialShardSpec,
       final String maxVersion
   ) throws IOException
   {
@@ -812,8 +812,8 @@ public class IndexerSQLMetadataStorageCoordinator implements IndexerMetadataStor
       if (existingChunks
           .stream()
           .flatMap(holder -> StreamSupport.stream(holder.getObject().spliterator(), false))
-          .anyMatch(chunk -> !chunk.getObject().getShardSpec().isCompatible(shardSpecFactory.getShardSpecClass()))) {
+          .anyMatch(chunk -> !chunk.getObject().getShardSpec().isCompatible(partialShardSpec.getShardSpecClass()))) {
-        // All existing segments should have a compatible shardSpec with shardSpecFactory.
+        // All existing segments should have a compatible shardSpec with partialShardSpec.
         return null;
       }
 
@@ -828,7 +828,7 @@ public class IndexerSQLMetadataStorageCoordinator implements IndexerMetadataStor
             // Here we check only the segments of the same shardSpec to find out the max partitionId.
             // Note that OverwriteShardSpec has the higher range for partitionId than others.
             // See PartitionIds.
-            .filter(chunk -> chunk.getObject().getShardSpec().getClass() == shardSpecFactory.getShardSpecClass())
+            .filter(chunk -> chunk.getObject().getShardSpec().getClass() == partialShardSpec.getShardSpecClass())
             .max(Comparator.comparing(chunk -> chunk.getObject().getShardSpec().getPartitionNum()))
             .map(chunk -> SegmentIdWithShardSpec.fromDataSegment(chunk.getObject()))
             .orElse(null);
@@ -845,7 +845,7 @@ public class IndexerSQLMetadataStorageCoordinator implements IndexerMetadataStor
       }
 
       maxId = pendings.stream()
-                      .filter(id -> id.getShardSpec().getClass() == shardSpecFactory.getShardSpecClass())
+                      .filter(id -> id.getShardSpec().getClass() == partialShardSpec.getShardSpecClass())
                       .max((id1, id2) -> {
                         final int versionCompare = id1.getVersion().compareTo(id2.getVersion());
                         if (versionCompare != 0) {
@@ -867,7 +867,7 @@ public class IndexerSQLMetadataStorageCoordinator implements IndexerMetadataStor
       }
 
       if (maxId == null) {
-        final ShardSpec shardSpec = shardSpecFactory.create(jsonMapper, null);
+        final ShardSpec shardSpec = partialShardSpec.complete(jsonMapper, null);
         String version = versionOfExistingChunks == null ? maxVersion : versionOfExistingChunks;
         return new SegmentIdWithShardSpec(dataSource, interval, version, shardSpec);
       } else if (!maxId.getInterval().equals(interval) || maxId.getVersion().compareTo(maxVersion) > 0) {
@@ -880,7 +880,7 @@ public class IndexerSQLMetadataStorageCoordinator implements IndexerMetadataStor
         );
         return null;
       } else {
-        final ShardSpec newShardSpec = shardSpecFactory.create(jsonMapper, maxId.getShardSpec());
+        final ShardSpec newShardSpec = partialShardSpec.complete(jsonMapper, maxId.getShardSpec());
         return new SegmentIdWithShardSpec(
             dataSource,
             maxId.getInterval(),

server/src/main/java/org/apache/druid/segment/realtime/appenderator/SegmentAllocator.java

@@ -21,25 +21,32 @@ package org.apache.druid.segment.realtime.appenderator;
 
 import org.apache.druid.data.input.InputRow;
 
+import javax.annotation.Nullable;
 import java.io.IOException;
 
 public interface SegmentAllocator
 {
   /**
-   * Allocates a new segment for a given timestamp.
+   * Allocates a new segment for a given timestamp. Even though its name is "allocate", this method is actually
+   * idempotent: given the same sequenceName, previousSegmentId, and skipSegmentLineageCheck, the implementation
+   * must return the same segment ID.
    *
    * @param row                     the event which triggered this allocation request
    * @param sequenceName            sequenceName for this allocation
-   * @param previousSegmentId       segment identifier returned on the previous call to allocate for your sequenceName
+   * @param previousSegmentId       segment identifier returned on the previous call to allocate for your sequenceName.
+   *                                When skipSegmentLineageCheck is false, this can be null if it is the first call
+   *                                for the same sequenceName.
+   *                                When skipSegmentLineageCheck is true, this will be ignored.
    * @param skipSegmentLineageCheck if true, perform lineage validation using previousSegmentId for this sequence.
    *                                Should be set to false if replica tasks would index events in same order
    *
    * @return the pending segment identifier, or null if it was impossible to allocate a new segment
    */
+  @Nullable
   SegmentIdWithShardSpec allocate(
       InputRow row,
       String sequenceName,
-      String previousSegmentId,
+      @Nullable String previousSegmentId,
       boolean skipSegmentLineageCheck
   ) throws IOException;
 }

server/src/test/java/org/apache/druid/metadata/IndexerSQLMetadataStorageCoordinatorTest.java

@@ -34,16 +34,16 @@ import org.apache.druid.java.util.common.StringUtils;
 import org.apache.druid.segment.TestHelper;
 import org.apache.druid.segment.realtime.appenderator.SegmentIdWithShardSpec;
 import org.apache.druid.timeline.DataSegment;
+import org.apache.druid.timeline.partition.HashBasedNumberedPartialShardSpec;
 import org.apache.druid.timeline.partition.HashBasedNumberedShardSpec;
-import org.apache.druid.timeline.partition.HashBasedNumberedShardSpecFactory;
 import org.apache.druid.timeline.partition.LinearShardSpec;
 import org.apache.druid.timeline.partition.NoneShardSpec;
+import org.apache.druid.timeline.partition.NumberedOverwritePartialShardSpec;
 import org.apache.druid.timeline.partition.NumberedOverwriteShardSpec;
-import org.apache.druid.timeline.partition.NumberedOverwritingShardSpecFactory;
+import org.apache.druid.timeline.partition.NumberedPartialShardSpec;
 import org.apache.druid.timeline.partition.NumberedShardSpec;
-import org.apache.druid.timeline.partition.NumberedShardSpecFactory;
+import org.apache.druid.timeline.partition.PartialShardSpec;
 import org.apache.druid.timeline.partition.PartitionIds;
-import org.apache.druid.timeline.partition.ShardSpecFactory;
 import org.assertj.core.api.Assertions;
 import org.joda.time.DateTime;
 import org.joda.time.Interval;
@@ -853,7 +853,7 @@ public class IndexerSQLMetadataStorageCoordinatorTest
   @Test
   public void testAllocatePendingSegment()
   {
-    final ShardSpecFactory shardSpecFactory = NumberedShardSpecFactory.instance();
+    final PartialShardSpec partialShardSpec = NumberedPartialShardSpec.instance();
     final String dataSource = "ds";
     final Interval interval = Intervals.of("2017-01-01/2017-02-01");
     final SegmentIdWithShardSpec identifier = coordinator.allocatePendingSegment(
@@ -861,7 +861,7 @@ public class IndexerSQLMetadataStorageCoordinatorTest
         "seq",
         null,
         interval,
-        shardSpecFactory,
+        partialShardSpec,
         "version",
         false
     );
@@ -873,7 +873,7 @@ public class IndexerSQLMetadataStorageCoordinatorTest
         "seq",
         identifier.toString(),
         interval,
-        shardSpecFactory,
+        partialShardSpec,
         identifier.getVersion(),
         false
     );
@@ -885,7 +885,7 @@ public class IndexerSQLMetadataStorageCoordinatorTest
         "seq",
         identifier1.toString(),
         interval,
-        shardSpecFactory,
+        partialShardSpec,
         identifier1.getVersion(),
         false
     );
@@ -897,7 +897,7 @@ public class IndexerSQLMetadataStorageCoordinatorTest
         "seq",
         identifier1.toString(),
         interval,
-        shardSpecFactory,
+        partialShardSpec,
         identifier1.getVersion(),
         false
     );
@@ -910,7 +910,7 @@ public class IndexerSQLMetadataStorageCoordinatorTest
         "seq1",
         null,
         interval,
-        shardSpecFactory,
+        partialShardSpec,
         "version",
         false
     );
@@ -921,7 +921,7 @@ public class IndexerSQLMetadataStorageCoordinatorTest
   @Test
   public void testDeletePendingSegment() throws InterruptedException
   {
-    final ShardSpecFactory shardSpecFactory = NumberedShardSpecFactory.instance();
+    final PartialShardSpec partialShardSpec = NumberedPartialShardSpec.instance();
     final String dataSource = "ds";
     final Interval interval = Intervals.of("2017-01-01/2017-02-01");
     String prevSegmentId = null;
@@ -934,7 +934,7 @@ public class IndexerSQLMetadataStorageCoordinatorTest
           "seq",
           prevSegmentId,
           interval,
-          shardSpecFactory,
+          partialShardSpec,
           "version",
           false
       );
@@ -949,7 +949,7 @@ public class IndexerSQLMetadataStorageCoordinatorTest
           "seq",
           prevSegmentId,
           interval,
-          shardSpecFactory,
+          partialShardSpec,
           "version",
           false
       );
@@ -973,7 +973,7 @@ public class IndexerSQLMetadataStorageCoordinatorTest
           "seq",
           prevSegmentId,
           interval,
-          new NumberedOverwritingShardSpecFactory(0, 1, (short) (i + 1)),
+          new NumberedOverwritePartialShardSpec(0, 1, (short) (i + 1)),
           "version",
           false
       );
@@ -1032,10 +1032,7 @@ public class IndexerSQLMetadataStorageCoordinatorTest
   @Test
   public void testAllocatePendingSegmentsForHashBasedNumberedShardSpec() throws IOException
   {
-    final ShardSpecFactory shardSpecFactory = new HashBasedNumberedShardSpecFactory(
+    final PartialShardSpec partialShardSpec = new HashBasedNumberedPartialShardSpec(null, 5);
-        null,
-        5
-    );
     final String dataSource = "ds";
     final Interval interval = Intervals.of("2017-01-01/2017-02-01");
 
@@ -1044,7 +1041,7 @@ public class IndexerSQLMetadataStorageCoordinatorTest
         "seq",
         null,
         interval,
-        shardSpecFactory,
+        partialShardSpec,
         "version",
         true
     );
@@ -1074,7 +1071,7 @@ public class IndexerSQLMetadataStorageCoordinatorTest
         "seq2",
         null,
         interval,
-        shardSpecFactory,
+        partialShardSpec,
         "version",
         true
     );
@@ -1104,7 +1101,7 @@ public class IndexerSQLMetadataStorageCoordinatorTest
         "seq3",
         null,
         interval,
-        new HashBasedNumberedShardSpecFactory(null, 3),
+        new HashBasedNumberedPartialShardSpec(null, 3),
         "version",
         true
     );

server/src/test/java/org/apache/druid/timeline/partition/HashBasedNumberedShardSpecTest.java

@@ -36,6 +36,8 @@ import org.junit.Test;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
 
 public class HashBasedNumberedShardSpecTest
 {
@@ -126,7 +128,6 @@ public class HashBasedNumberedShardSpecTest
   @Test
   public void testIsInChunk()
   {
-
     List<ShardSpec> specs = new ArrayList<>();
     for (int i = 0; i < 3; i++) {
       specs.add(new HashOverridenShardSpec(i, 3));
@@ -137,7 +138,20 @@ public class HashBasedNumberedShardSpecTest
     assertExistsInOneSpec(specs, new HashInputRow(0));
     assertExistsInOneSpec(specs, new HashInputRow(1000));
     assertExistsInOneSpec(specs, new HashInputRow(-1000));
+  }
 
+  @Test
+  public void testIsInChunkWithMorePartitionsBeyondNumBucketsReturningTrue()
+  {
+    final int numBuckets = 3;
+    final List<ShardSpec> specs = IntStream.range(0, 10)
+                                           .mapToObj(i -> new HashOverridenShardSpec(i, numBuckets))
+                                           .collect(Collectors.toList());
+
+    for (int i = 0; i < 10; i++) {
+      final InputRow row = new HashInputRow(numBuckets * 10000 + i);
+      Assert.assertTrue(specs.get(i).isInChunk(row.getTimestampFromEpoch(), row));
+    }
   }
 
   @Test
@@ -186,10 +200,7 @@ public class HashBasedNumberedShardSpecTest
 
   public static class HashOverridenShardSpec extends HashBasedNumberedShardSpec
   {
-    public HashOverridenShardSpec(
+    public HashOverridenShardSpec(int partitionNum, int partitions)
-        int partitionNum,
-        int partitions
-    )
     {
       super(partitionNum, partitions, null, ServerTestHelper.MAPPER);
     }