Part 2 of changes for SQL Compatible Null Handling (#5958)

* Part 2 of changes for SQL Compatible Null Handling

* Review comments - break lines longer than 120 characters

* review comments

* review comments

* fix license

* fix test failure

* fix CalciteQueryTest failure

* Null Handling - Review comments

* review comments

* review comments

* fix checkstyle

* fix checkstyle

* remove unrelated change

* fix test failure

* fix failing test

* fix travis failures

* Make StringLast and StringFirst aggregators nullable and fix travis failures

.travis.yml

@@ -33,6 +33,15 @@ matrix:
         - unset _JAVA_OPTIONS
       script: echo "MAVEN_OPTS='-Xmx512m'" > ~/.mavenrc && mvn test -B -Pparallel-test -Dmaven.fork.count=2 -pl processing
 
+      # processing module tests with SQL Compatibility enabled
+    - sudo: false
+      env:
+        - NAME="processing module test with SQL Compatibility"
+      install: echo "MAVEN_OPTS='-Xmx3000m'" > ~/.mavenrc && mvn install -q -ff -DskipTests -B
+      before_script:
+        - unset _JAVA_OPTIONS
+      script: echo "MAVEN_OPTS='-Xmx512m'" > ~/.mavenrc && mvn test -B -Pparallel-test -Dmaven.fork.count=2 -Ddruid.generic.useDefaultValueForNull=false -pl processing
+
       # server module test
     - sudo: false
       env:
@@ -43,6 +52,17 @@ matrix:
       # Server module test is run without the parallel-test option because it's memory sensitive and often fails with that option.
       script: echo "MAVEN_OPTS='-Xmx512m'" > ~/.mavenrc && mvn test -B -pl server
 
+      # server module test with SQL Compatibility enabled
+    - sudo: false
+      env:
+        - NAME="server module test with SQL Compatibility enabled"
+      install: echo "MAVEN_OPTS='-Xmx3000m'" > ~/.mavenrc && mvn install -q -ff -DskipTests -B
+      before_script:
+        - unset _JAVA_OPTIONS
+      # Server module test is run without the parallel-test option because it's memory sensitive and often fails with that option.
+      script: echo "MAVEN_OPTS='-Xmx512m'" > ~/.mavenrc && mvn test -B -pl server -Ddruid.generic.useDefaultValueForNull=false
+
+
       # other modules test
     - sudo: false
       env:
@@ -53,6 +73,16 @@ matrix:
         - unset _JAVA_OPTIONS
       script: echo "MAVEN_OPTS='-Xmx512m'" > ~/.mavenrc && mvn test -B -Pparallel-test -Dmaven.fork.count=2 -pl '!processing,!server'
 
+      # other modules test with SQL Compatibility enabled
+    - sudo: false
+      env:
+        - NAME="other modules test with SQL Compatibility"
+        - AWS_REGION=us-east-1 # set a aws region for unit tests
+      install: echo "MAVEN_OPTS='-Xmx3000m'" > ~/.mavenrc && mvn install -q -ff -DskipTests -B
+      before_script:
+        - unset _JAVA_OPTIONS
+      script: echo "MAVEN_OPTS='-Xmx512m'" > ~/.mavenrc && mvn test -B -Pparallel-test -Dmaven.fork.count=2 -Ddruid.generic.useDefaultValueForNull=false -pl '!processing,!server'
+
       # run integration tests
     - sudo: required
       services:

api/src/main/java/io/druid/data/input/Rows.java

@@ -23,9 +23,11 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Maps;
 import com.google.common.primitives.Longs;
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.StringUtils;
 import io.druid.java.util.common.parsers.ParseException;
 
+import javax.annotation.Nullable;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
@@ -92,10 +94,11 @@ public class Rows
    * @throws NullPointerException if the string is null
    * @throws ParseException       if the column cannot be converted to a number
    */
+  @Nullable
   public static Number objectToNumber(final String name, final Object inputValue)
   {
     if (inputValue == null) {
-      return Rows.LONG_ZERO;
+      return NullHandling.defaultLongValue();
     }
 
     if (inputValue instanceof Number) {

benchmarks/src/main/java/io/druid/benchmark/FilterPartitionBenchmark.java

@@ -21,12 +21,12 @@ package io.druid.benchmark;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.base.Predicate;
-import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import com.google.common.io.Files;
 import io.druid.benchmark.datagen.BenchmarkDataGenerator;
 import io.druid.benchmark.datagen.BenchmarkSchemaInfo;
 import io.druid.benchmark.datagen.BenchmarkSchemas;
+import io.druid.common.config.NullHandling;
 import io.druid.data.input.InputRow;
 import io.druid.hll.HyperLogLogHash;
 import io.druid.jackson.DefaultObjectMapper;
@@ -557,7 +557,7 @@ public class FilterPartitionBenchmark
       if (extractionFn == null) {
         return new NoBitmapSelectorFilter(dimension, value);
       } else {
-        final String valueOrNull = Strings.emptyToNull(value);
+        final String valueOrNull = NullHandling.emptyToNullIfNeeded(value);
 
         final DruidPredicateFactory predicateFactory = new DruidPredicateFactory()
         {

codestyle/checkstyle.xml

@@ -171,7 +171,6 @@
       <property name="illegalPattern" value="true"/>
       <property name="message" value="Use java.lang.Primitive.BYTES instead."/>
     </module>
-
     <!-- This regex should be replaced with an IntelliJ inspection when teamcity.jetbrains.com updates to at least IntelliJ 2018.1 (currently it uses 2017.2) -->
     <module name="Regexp">
       <property name="format" value='[a-z][a-zA-Z0-9_]*\.equals\((\"|[A-Z_]+\))'/>
@@ -184,5 +183,15 @@
       <property name="illegalPattern" value="true"/>
       <property name="message" value='Use toArray(new Object[0]) instead'/>
     </module>
+    <module name="Regexp">
+      <property name="format" value="Strings.emptyToNull"/>
+      <property name="illegalPattern" value="true"/>
+      <property name="message" value="Use io.druid.common.config.NullHandling.emptyToNullIfNeeded instead"/>
+    </module>
+    <module name="Regexp">
+      <property name="format" value="Strings.nullToEmpty"/>
+      <property name="illegalPattern" value="true"/>
+      <property name="message" value="Use io.druid.common.config.NullHandling.nullToEmptyIfNeeded instead"/>
+    </module>
   </module>
 </module>

common/src/main/java/io/druid/math/expr/Evals.java

@@ -19,7 +19,7 @@
 
 package io.druid.math.expr;
 
-import com.google.common.base.Strings;
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.logger.Logger;
 
 import java.util.Arrays;
@@ -83,6 +83,6 @@ public class Evals
 
   public static boolean asBoolean(String x)
   {
-    return !Strings.isNullOrEmpty(x) && Boolean.valueOf(x);
+    return !NullHandling.isNullOrEquivalent(x) && Boolean.valueOf(x);
   }
 }

common/src/main/java/io/druid/math/expr/Expr.java

@@ -272,6 +272,9 @@ class UnaryMinusExpr extends UnaryExpr
   public ExprEval eval(ObjectBinding bindings)
   {
     ExprEval ret = expr.eval(bindings);
+    if (NullHandling.sqlCompatible() && (ret.value() == null)) {
+      return ExprEval.of(null);
+    }
     if (ret.type() == ExprType.LONG) {
       return ExprEval.of(-ret.asLong());
     }
@@ -307,6 +310,9 @@ class UnaryNotExpr extends UnaryExpr
   public ExprEval eval(ObjectBinding bindings)
   {
     ExprEval ret = expr.eval(bindings);
+    if (NullHandling.sqlCompatible() && (ret.value() == null)) {
+      return ExprEval.of(null);
+    }
     // conforming to other boolean-returning binary operators
     ExprType retType = ret.type() == ExprType.DOUBLE ? ExprType.DOUBLE : ExprType.LONG;
     return ExprEval.of(!ret.asBoolean(), retType);
@@ -365,15 +371,21 @@ abstract class BinaryEvalOpExprBase extends BinaryOpExprBase
 
     // Result of any Binary expressions is null if any of the argument is null.
     // e.g "select null * 2 as c;" or "select null + 1 as c;" will return null as per Standard SQL spec.
-    if (NullHandling.sqlCompatible() && (leftVal.isNull() || rightVal.isNull())) {
+    if (NullHandling.sqlCompatible() && (leftVal.value() == null || rightVal.value() == null)) {
       return ExprEval.of(null);
     }
 
     if (leftVal.type() == ExprType.STRING && rightVal.type() == ExprType.STRING) {
       return evalString(leftVal.asString(), rightVal.asString());
     } else if (leftVal.type() == ExprType.LONG && rightVal.type() == ExprType.LONG) {
+      if (NullHandling.sqlCompatible() && (leftVal.isNumericNull() || rightVal.isNumericNull())) {
+        return ExprEval.of(null);
+      }
       return ExprEval.of(evalLong(leftVal.asLong(), rightVal.asLong()));
     } else {
+      if (NullHandling.sqlCompatible() && (leftVal.isNumericNull() || rightVal.isNumericNull())) {
+        return ExprEval.of(null);
+      }
       return ExprEval.of(evalDouble(leftVal.asDouble(), rightVal.asDouble()));
     }
   }

common/src/main/java/io/druid/math/expr/ExprEval.java

@@ -19,9 +19,7 @@
 
 package io.druid.math.expr;
 
-import com.google.common.base.Preconditions;
 import com.google.common.primitives.Doubles;
-import com.google.common.primitives.Ints;
 import io.druid.common.config.NullHandling;
 import io.druid.common.guava.GuavaUtils;
 import io.druid.java.util.common.IAE;
@@ -32,7 +30,7 @@ import javax.annotation.Nullable;
  */
 public abstract class ExprEval<T>
 {
-  public static ExprEval ofLong(Number longValue)
+  public static ExprEval ofLong(@Nullable Number longValue)
   {
     return new LongExprEval(longValue);
   }
@@ -42,7 +40,7 @@ public abstract class ExprEval<T>
     return new LongExprEval(longValue);
   }
 
-  public static ExprEval ofDouble(Number doubleValue)
+  public static ExprEval ofDouble(@Nullable Number doubleValue)
   {
     return new DoubleExprEval(doubleValue);
   }
@@ -71,7 +69,7 @@ public abstract class ExprEval<T>
     }
   }
 
-  public static ExprEval bestEffortOf(Object val)
+  public static ExprEval bestEffortOf(@Nullable Object val)
   {
     if (val instanceof ExprEval) {
       return (ExprEval) val;
@@ -85,6 +83,7 @@ public abstract class ExprEval<T>
     return new StringExprEval(val == null ? null : String.valueOf(val));
   }
 
+  @Nullable
   final T value;
 
   private ExprEval(T value)
@@ -99,10 +98,10 @@ public abstract class ExprEval<T>
     return value;
   }
 
-  public boolean isNull()
+  /**
-  {
+   * returns true if numeric primitive value for this ExprEval is null, otherwise false.
-    return value == null;
+   */
-  }
+  public abstract boolean isNumericNull();
 
   public abstract int asInt();
 
@@ -125,7 +124,7 @@ public abstract class ExprEval<T>
   private abstract static class NumericExprEval extends ExprEval<Number>
   {
 
-    private NumericExprEval(Number value)
+    private NumericExprEval(@Nullable Number value)
     {
       super(value);
     }
@@ -147,13 +146,19 @@ public abstract class ExprEval<T>
     {
       return value.doubleValue();
     }
+
+    @Override
+    public boolean isNumericNull()
+    {
+      return value == null;
+    }
   }
 
   private static class DoubleExprEval extends NumericExprEval
   {
-    private DoubleExprEval(Number value)
+    private DoubleExprEval(@Nullable Number value)
     {
-      super(Preconditions.checkNotNull(value, "value"));
+      super(value == null ? NullHandling.defaultDoubleValue() : value);
     }
 
     @Override
@@ -175,7 +180,7 @@ public abstract class ExprEval<T>
         case DOUBLE:
           return this;
         case LONG:
-          return ExprEval.of(asLong());
+          return ExprEval.of(value == null ? null : asLong());
         case STRING:
           return ExprEval.of(asString());
       }
@@ -191,9 +196,9 @@ public abstract class ExprEval<T>
 
   private static class LongExprEval extends NumericExprEval
   {
-    private LongExprEval(Number value)
+    private LongExprEval(@Nullable Number value)
     {
-      super(Preconditions.checkNotNull(value, "value"));
+      super(value == null ? NullHandling.defaultLongValue() : value);
     }
 
     @Override
@@ -213,7 +218,7 @@ public abstract class ExprEval<T>
     {
       switch (castTo) {
         case DOUBLE:
-          return ExprEval.of(asDouble());
+          return ExprEval.of(value == null ? null : asDouble());
         case LONG:
           return this;
         case STRING:
@@ -231,6 +236,8 @@ public abstract class ExprEval<T>
 
   private static class StringExprEval extends ExprEval<String>
   {
+    private Number numericVal;
+
     private StringExprEval(@Nullable String value)
     {
       super(NullHandling.emptyToNullIfNeeded(value));
@@ -245,36 +252,63 @@ public abstract class ExprEval<T>
     @Override
     public final int asInt()
     {
-      if (value == null) {
+      Number number = asNumber();
+      if (number == null) {
         assert NullHandling.replaceWithDefault();
         return 0;
       }
-
+      return number.intValue();
-      final Integer theInt = Ints.tryParse(value);
-      assert NullHandling.replaceWithDefault() || theInt != null;
-      return theInt == null ? 0 : theInt;
     }
 
     @Override
     public final long asLong()
     {
-      // GuavaUtils.tryParseLong handles nulls, no need for special null handling here.
+      Number number = asNumber();
-      final Long theLong = GuavaUtils.tryParseLong(value);
+      if (number == null) {
-      assert NullHandling.replaceWithDefault() || theLong != null;
+        assert NullHandling.replaceWithDefault();
-      return theLong == null ? 0L : theLong;
+        return 0L;
+      }
+      return number.longValue();
     }
 
     @Override
     public final double asDouble()
     {
-      if (value == null) {
+      Number number = asNumber();
+      if (number == null) {
         assert NullHandling.replaceWithDefault();
-        return 0.0;
+        return 0.0d;
+      }
+      return number.doubleValue();
     }
 
-      final Double theDouble = Doubles.tryParse(value);
+    @Nullable
-      assert NullHandling.replaceWithDefault() || theDouble != null;
+    private Number asNumber()
-      return theDouble == null ? 0.0 : theDouble;
+    {
+      if (value == null) {
+        return null;
+      }
+      if (numericVal != null) {
+        // Optimization for non-null case.
+        return numericVal;
+      }
+      Number rv;
+      Long v = GuavaUtils.tryParseLong(value);
+      // Do NOT use ternary operator here, because it makes Java to convert Long to Double
+      if (v != null) {
+        rv = v;
+      } else {
+        rv = Doubles.tryParse(value);
+      }
+
+      numericVal = rv;
+      return rv;
+    }
+
+    @Override
+    public boolean isNumericNull()
+    {
+      return asNumber() == null;
     }
 
     @Override
@@ -288,9 +322,9 @@ public abstract class ExprEval<T>
     {
       switch (castTo) {
         case DOUBLE:
-          return ExprEval.of(asDouble());
+          return ExprEval.ofDouble(asNumber());
         case LONG:
-          return ExprEval.of(asLong());
+          return ExprEval.ofLong(asNumber());
         case STRING:
           return this;
       }

common/src/main/java/io/druid/math/expr/Function.java

@@ -74,7 +74,7 @@ interface Function
     @Override
     protected final ExprEval eval(ExprEval param)
     {
-      if (NullHandling.sqlCompatible() && param.isNull()) {
+      if (NullHandling.sqlCompatible() && param.isNumericNull()) {
         return ExprEval.of(null);
       }
       if (param.type() == ExprType.LONG) {
@@ -796,6 +796,9 @@ interface Function
     @Override
     protected ExprEval eval(ExprEval x, ExprEval y)
     {
+      if (NullHandling.sqlCompatible() && x.value() == null) {
+        return ExprEval.of(null);
+      }
       ExprType castTo;
       try {
         castTo = ExprType.valueOf(StringUtils.toUpperCase(y.asString()));
@@ -880,7 +883,7 @@ interface Function
         throw new IAE("Function[%s] needs 2 arguments", name());
       }
       final ExprEval eval = args.get(0).eval(bindings);
-      return eval.isNull() ? args.get(1).eval(bindings) : eval;
+      return eval.value() == null ? args.get(1).eval(bindings) : eval;
     }
   }
 
@@ -937,7 +940,7 @@ interface Function
       }
 
       final String arg = args.get(0).eval(bindings).asString();
-      return arg == null ? ExprEval.of(0) : ExprEval.of(arg.length());
+      return arg == null ? ExprEval.ofLong(NullHandling.defaultLongValue()) : ExprEval.of(arg.length());
     }
   }
 
@@ -1094,7 +1097,7 @@ interface Function
       }
 
       final ExprEval expr = args.get(0).eval(bindings);
-      return ExprEval.of(expr.isNull(), ExprType.LONG);
+      return ExprEval.of(expr.value() == null, ExprType.LONG);
     }
   }
 
@@ -1114,7 +1117,7 @@ interface Function
       }
 
       final ExprEval expr = args.get(0).eval(bindings);
-      return ExprEval.of(!expr.isNull(), ExprType.LONG);
+      return ExprEval.of(expr.value() != null, ExprType.LONG);
     }
   }
 }

common/src/test/java/io/druid/math/expr/EvalTest.java

@@ -140,11 +140,10 @@ public class EvalTest
     Assert.assertEquals(1271055781L, evalLong("unix_timestamp('2010-04-12T07:03:01')", bindings));
     Assert.assertEquals(1271023381L, evalLong("unix_timestamp('2010-04-12T07:03:01+09:00')", bindings));
     Assert.assertEquals(1271023381L, evalLong("unix_timestamp('2010-04-12T07:03:01.419+09:00')", bindings));
-    if (NullHandling.replaceWithDefault()) {
+    Assert.assertEquals(
-      Assert.assertEquals("NULL", eval("nvl(if(x == 9223372036854775807, '', 'x'), 'NULL')", bindings).asString());
+        NullHandling.replaceWithDefault() ? "NULL" : "",
-    } else {
+        eval("nvl(if(x == 9223372036854775807, '', 'x'), 'NULL')", bindings).asString()
-      Assert.assertEquals("", eval("nvl(if(x == 9223372036854775807, '', 'x'), 'NULL')", bindings).asString());
+    );
-    }
     Assert.assertEquals("x", eval("nvl(if(x == 9223372036854775806, '', 'x'), 'NULL')", bindings).asString());
   }
 

common/src/test/java/io/druid/math/expr/FunctionTest.java

@@ -88,7 +88,7 @@ public class FunctionTest
   public void testStrlen()
   {
     assertExpr("strlen(x)", 3L);
-    assertExpr("strlen(nonexistent)", 0L);
+    assertExpr("strlen(nonexistent)", NullHandling.defaultLongValue());
   }
 
   @Test

docs/content/configuration/auth.md

@@ -12,7 +12,7 @@ layout: doc_page
 |`druid.auth.unsecuredPaths`| List of Strings|List of paths for which security checks will not be performed. All requests to these paths will be allowed.|[]|no|
 |`druid.auth.allowUnauthenticatedHttpOptions`|Boolean|If true, skip authentication checks for HTTP OPTIONS requests. This is needed for certain use cases, such as supporting CORS pre-flight requests. Note that disabling authentication checks for OPTIONS requests will allow unauthenticated users to determine what Druid endpoints are valid (by checking if the OPTIONS request returns a 200 instead of 404), so enabling this option may reveal information about server configuration, including information about what extensions are loaded (if those extensions add endpoints).|false|no|
 
-## Enabling Authentication/Authorization
+## Enabling Authentication/AuthorizationLoadingLookupTest
 
 ## Authenticator Chain
 Authentication decisions are handled by a chain of Authenticator instances. A request will be checked by Authenticators in the sequence defined by the `druid.auth.authenticatorChain`.

extensions-core/datasketches/src/main/java/io/druid/query/aggregation/datasketches/quantiles/DoublesSketchAggregatorFactory.java

@@ -106,13 +106,13 @@ public class DoublesSketchAggregatorFactory extends AggregatorFactory
       if (selector instanceof NilColumnValueSelector) {
         return new DoublesSketchNoOpBufferAggregator();
       }
-      return new DoublesSketchBuildBufferAggregator(selector, k, getMaxIntermediateSize());
+      return new DoublesSketchBuildBufferAggregator(selector, k, getMaxIntermediateSizeWithNulls());
     }
     final ColumnValueSelector<DoublesSketch> selector = metricFactory.makeColumnValueSelector(fieldName);
     if (selector instanceof NilColumnValueSelector) {
       return new DoublesSketchNoOpBufferAggregator();
     }
-    return new DoublesSketchMergeBufferAggregator(selector, k, getMaxIntermediateSize());
+    return new DoublesSketchMergeBufferAggregator(selector, k, getMaxIntermediateSizeWithNulls());
   }
 
   @Override

extensions-core/datasketches/src/main/java/io/druid/query/aggregation/datasketches/quantiles/DoublesSketchMergeAggregatorFactory.java

@@ -57,7 +57,7 @@ public class DoublesSketchMergeAggregatorFactory extends DoublesSketchAggregator
     if (selector instanceof NilColumnValueSelector) {
       return new DoublesSketchNoOpBufferAggregator();
     }
-    return new DoublesSketchMergeBufferAggregator(selector, getK(), getMaxIntermediateSize());
+    return new DoublesSketchMergeBufferAggregator(selector, getK(), getMaxIntermediateSizeWithNulls());
   }
 
 }

extensions-core/datasketches/src/main/java/io/druid/query/aggregation/datasketches/theta/SketchAggregatorFactory.java

@@ -74,7 +74,7 @@ public abstract class SketchAggregatorFactory extends AggregatorFactory
   public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
   {
     BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(fieldName);
-    return new SketchBufferAggregator(selector, size, getMaxIntermediateSize());
+    return new SketchBufferAggregator(selector, size, getMaxIntermediateSizeWithNulls());
   }
 
   @Override

extensions-core/datasketches/src/main/java/io/druid/query/aggregation/datasketches/tuple/ArrayOfDoublesSketchAggregatorFactory.java

@@ -125,7 +125,7 @@ public class ArrayOfDoublesSketchAggregatorFactory extends AggregatorFactory
           selector,
           nominalEntries,
           numberOfValues,
-          getMaxIntermediateSize()
+          getMaxIntermediateSizeWithNulls()
       );
     }
     // input is raw data (key and array of values), use build aggregator
@@ -143,7 +143,7 @@ public class ArrayOfDoublesSketchAggregatorFactory extends AggregatorFactory
         keySelector,
         valueSelectors,
         nominalEntries,
-        getMaxIntermediateSize()
+        getMaxIntermediateSizeWithNulls()
     );
   }
 

extensions-core/histogram/src/main/java/io/druid/query/aggregation/histogram/ApproximateHistogramAggregator.java

@@ -20,6 +20,7 @@
 package io.druid.query.aggregation.histogram;
 
 import com.google.common.primitives.Longs;
+import io.druid.common.config.NullHandling;
 import io.druid.query.aggregation.Aggregator;
 import io.druid.segment.BaseFloatColumnValueSelector;
 
@@ -59,8 +60,13 @@ public class ApproximateHistogramAggregator implements Aggregator
   @Override
   public void aggregate()
   {
+    // In case of ExpressionColumnValueSelector isNull will compute the expression and then give the result,
+    // the check for is NullHandling.replaceWithDefault is there to not have any performance impact of calling
+    // isNull for default case.
+    if (NullHandling.replaceWithDefault() || !selector.isNull()) {
       histogram.offer(selector.getFloat());
     }
+  }
 
   @Override
   public Object get()

extensions-core/histogram/src/test/java/io/druid/query/aggregation/histogram/ApproximateHistogramAggregationTest.java

@@ -20,6 +20,7 @@
 package io.druid.query.aggregation.histogram;
 
 import com.google.common.collect.Lists;
+import io.druid.common.config.NullHandling;
 import io.druid.data.input.MapBasedRow;
 import io.druid.java.util.common.granularity.Granularities;
 import io.druid.java.util.common.guava.Sequence;
@@ -79,11 +80,15 @@ public class ApproximateHistogramAggregationTest
   @Test
   public void testIngestWithNullsToZeroAndQuery() throws Exception
   {
+    // Nulls are ignored and not replaced with default for SQL compatible null handling.
+    // This is already tested in testIngestWithNullsIgnoredAndQuery()
+    if (NullHandling.replaceWithDefault()) {
       MapBasedRow row = ingestAndQuery(false);
-    Assert.assertEquals(0.0, row.getMetric("index_min").floatValue(), 0.0001);
+      Assert.assertEquals(0.0F, row.getMetric("index_min"));
       Assert.assertEquals(135.109191, row.getMetric("index_max").floatValue(), 0.0001);
       Assert.assertEquals(131.428176, row.getMetric("index_quantile").floatValue(), 0.0001);
     }
+  }
 
   private MapBasedRow ingestAndQuery(boolean ignoreNulls) throws Exception
   {

extensions-core/histogram/src/test/java/io/druid/query/aggregation/histogram/ApproximateHistogramAggregatorTest.java

@@ -48,7 +48,7 @@ public class ApproximateHistogramAggregatorTest
     );
     ApproximateHistogramBufferAggregator agg = new ApproximateHistogramBufferAggregator(selector, resolution);
 
-    ByteBuffer buf = ByteBuffer.allocate(factory.getMaxIntermediateSize());
+    ByteBuffer buf = ByteBuffer.allocate(factory.getMaxIntermediateSizeWithNulls());
     int position = 0;
 
     agg.init(buf, position);

extensions-core/histogram/src/test/java/io/druid/query/aggregation/histogram/sql/QuantileSqlAggregatorTest.java

@@ -23,6 +23,7 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.granularity.Granularities;
 import io.druid.query.Druids;
 import io.druid.query.QueryDataSource;
@@ -312,9 +313,12 @@ public class QuantileSqlAggregatorTest extends CalciteTestBase
 
       // Verify results
       final List<Object[]> results = plannerResult.run().toList();
-      final List<Object[]> expectedResults = ImmutableList.of(
+      final List<Object[]> expectedResults;
-          new Object[]{7.0, 8.26386833190918}
+      if (NullHandling.replaceWithDefault()) {
-      );
+        expectedResults = ImmutableList.of(new Object[]{7.0, 8.26386833190918});
+      } else {
+        expectedResults = ImmutableList.of(new Object[]{5.25, 6.59091854095459});
+      }
       Assert.assertEquals(expectedResults.size(), results.size());
       for (int i = 0; i < expectedResults.size(); i++) {
         Assert.assertArrayEquals(expectedResults.get(i), results.get(i));

extensions-core/kafka-indexing-service/src/test/java/io/druid/indexing/kafka/KafkaIndexTaskTest.java

@@ -115,6 +115,7 @@ import io.druid.query.timeseries.TimeseriesQueryEngine;
 import io.druid.query.timeseries.TimeseriesQueryQueryToolChest;
 import io.druid.query.timeseries.TimeseriesQueryRunnerFactory;
 import io.druid.query.timeseries.TimeseriesResultValue;
+import io.druid.segment.DimensionHandlerUtils;
 import io.druid.segment.IndexIO;
 import io.druid.segment.QueryableIndex;
 import io.druid.segment.TestHelper;
@@ -2244,7 +2245,7 @@ public class KafkaIndexTaskTest
     List<Result<TimeseriesResultValue>> results =
         task.getQueryRunner(query).run(wrap(query), ImmutableMap.of()).toList();
 
-    return results.isEmpty() ? 0 : results.get(0).getValue().getLongMetric("rows");
+    return results.isEmpty() ? 0L : DimensionHandlerUtils.nullToZero(results.get(0).getValue().getLongMetric("rows"));
   }
 
   private static byte[] JB(String timestamp, String dim1, String dim2, String dimLong, String dimFloat, String met1)

extensions-core/lookups-cached-global/src/main/java/io/druid/query/lookup/namespace/UriExtractionNamespace.java

@@ -35,6 +35,7 @@ import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import io.druid.guice.annotations.Json;
 import io.druid.java.util.common.IAE;
+import io.druid.java.util.common.StringUtils;
 import io.druid.java.util.common.UOE;
 import io.druid.java.util.common.jackson.JacksonUtils;
 import io.druid.java.util.common.parsers.CSVParser;
@@ -396,8 +397,8 @@ public class UriExtractionNamespace implements ExtractionNamespace
           "Must specify more than one column to have a key value pair"
       );
       final DelimitedParser delegate = new DelimitedParser(
-          Strings.emptyToNull(delimiter),
+          StringUtils.emptyToNullNonDruidDataString(delimiter),
-          Strings.emptyToNull(listDelimiter),
+          StringUtils.emptyToNullNonDruidDataString(listDelimiter),
           hasHeaderRow,
           skipHeaderRows
       );

extensions-core/lookups-cached-global/src/test/java/io/druid/server/lookup/namespace/cache/JdbcExtractionNamespaceTest.java

@@ -19,15 +19,15 @@
 
 package io.druid.server.lookup.namespace.cache;
 
-import com.google.common.base.Strings;
 import com.google.common.base.Throwables;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.util.concurrent.ListenableFuture;
 import com.google.common.util.concurrent.ListeningExecutorService;
 import com.google.common.util.concurrent.MoreExecutors;
-import io.druid.java.util.common.StringUtils;
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.concurrent.Execs;
+import io.druid.java.util.common.StringUtils;
 import io.druid.java.util.common.io.Closer;
 import io.druid.java.util.common.lifecycle.Lifecycle;
 import io.druid.java.util.common.logger.Logger;
@@ -382,7 +382,7 @@ public class JdbcExtractionNamespaceTest
         String key = e.getKey();
         String[] val = e.getValue();
         String field = val[0];
-        Assert.assertEquals("non-null check", Strings.emptyToNull(field), Strings.emptyToNull(map.get(key)));
+        Assert.assertEquals("non-null check", NullHandling.emptyToNullIfNeeded(field), NullHandling.emptyToNullIfNeeded(map.get(key)));
       }
       Assert.assertEquals("null check", null, map.get("baz"));
     }
@@ -412,9 +412,9 @@ public class JdbcExtractionNamespaceTest
         String filterVal = val[1];
 
         if ("1".equals(filterVal)) {
-          Assert.assertEquals("non-null check", Strings.emptyToNull(field), Strings.emptyToNull(map.get(key)));
+          Assert.assertEquals("non-null check", NullHandling.emptyToNullIfNeeded(field), NullHandling.emptyToNullIfNeeded(map.get(key)));
         } else {
-          Assert.assertEquals("non-null check", null, Strings.emptyToNull(map.get(key)));
+          Assert.assertEquals("non-null check", null, NullHandling.emptyToNullIfNeeded(map.get(key)));
         }
       }
     }

extensions-core/lookups-cached-single/src/main/java/io/druid/server/lookup/LoadingLookup.java

@@ -21,11 +21,12 @@ package io.druid.server.lookup;
 
 
 import com.google.common.base.Preconditions;
-import com.google.common.base.Strings;
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.logger.Logger;
 import io.druid.query.lookup.LookupExtractor;
 import io.druid.server.lookup.cache.loading.LoadingCache;
 
+import javax.annotation.Nullable;
 import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.Callable;
@@ -62,15 +63,19 @@ public class LoadingLookup extends LookupExtractor
 
 
   @Override
-  public String apply(final String key)
+  public String apply(@Nullable final String key)
   {
-    if (key == null) {
+    String keyEquivalent = NullHandling.nullToEmptyIfNeeded(key);
+    if (keyEquivalent == null) {
+      // valueEquivalent is null only for SQL Compatible Null Behavior
+      // otherwise null will be replaced with empty string in nullToEmptyIfNeeded above.
       return null;
     }
+
     final String presentVal;
     try {
-      presentVal = loadingCache.get(key, new ApplyCallable(key));
+      presentVal = loadingCache.get(keyEquivalent, new ApplyCallable(keyEquivalent));
-      return Strings.emptyToNull(presentVal);
+      return NullHandling.emptyToNullIfNeeded(presentVal);
     }
     catch (ExecutionException e) {
       LOGGER.debug("value not found for key [%s]", key);
@@ -79,15 +84,18 @@ public class LoadingLookup extends LookupExtractor
   }
 
   @Override
-  public List<String> unapply(final String value)
+  public List<String> unapply(@Nullable final String value)
   {
-    // null value maps to empty list
+    String valueEquivalent = NullHandling.nullToEmptyIfNeeded(value);
-    if (value == null) {
+    if (valueEquivalent == null) {
+      // valueEquivalent is null only for SQL Compatible Null Behavior
+      // otherwise null will be replaced with empty string in nullToEmptyIfNeeded above.
+      // null value maps to empty list when SQL Compatible
       return Collections.EMPTY_LIST;
     }
     final List<String> retList;
     try {
-      retList = reverseLoadingCache.get(value, new UnapplyCallable(value));
+      retList = reverseLoadingCache.get(valueEquivalent, new UnapplyCallable(valueEquivalent));
       return retList;
     }
     catch (ExecutionException e) {
@@ -131,8 +139,9 @@ public class LoadingLookup extends LookupExtractor
     @Override
     public String call()
     {
+      // When SQL compatible null handling is disabled,
       // avoid returning null and return an empty string to cache it.
-      return Strings.nullToEmpty(dataFetcher.fetch(key));
+      return NullHandling.nullToEmptyIfNeeded(dataFetcher.fetch(key));
     }
   }
 

extensions-core/lookups-cached-single/src/main/java/io/druid/server/lookup/PollingLookup.java

@@ -20,11 +20,11 @@
 package io.druid.server.lookup;
 
 import com.google.common.base.Preconditions;
-import com.google.common.base.Strings;
 import com.google.common.util.concurrent.ListenableFuture;
 import com.google.common.util.concurrent.ListeningScheduledExecutorService;
 import com.google.common.util.concurrent.MoreExecutors;
 
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.concurrent.Execs;
 import io.druid.java.util.common.ISE;
 import io.druid.java.util.common.logger.Logger;
@@ -33,7 +33,8 @@ import io.druid.server.lookup.cache.polling.OnHeapPollingCache;
 import io.druid.server.lookup.cache.polling.PollingCache;
 import io.druid.server.lookup.cache.polling.PollingCacheFactory;
 
-import javax.validation.constraints.NotNull;
+import javax.annotation.Nullable;
+import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
@@ -107,8 +108,15 @@ public class PollingLookup extends LookupExtractor
   }
 
   @Override
-  public String apply(@NotNull String key)
+  @Nullable
+  public String apply(@Nullable String key)
   {
+    String keyEquivalent = NullHandling.nullToEmptyIfNeeded(key);
+    if (keyEquivalent == null) {
+      // valueEquivalent is null only for SQL Compatible Null Behavior
+      // otherwise null will be replaced with empty string in nullToEmptyIfNeeded above.
+      return null;
+    }
     final CacheRefKeeper cacheRefKeeper = refOfCacheKeeper.get();
     if (cacheRefKeeper == null) {
       throw new ISE("Cache reference is null WTF");
@@ -117,9 +125,9 @@ public class PollingLookup extends LookupExtractor
     try {
       if (cache == null) {
         // it must've been closed after swapping while I was getting it.  Try again.
-        return this.apply(key);
+        return this.apply(keyEquivalent);
       }
-      return Strings.emptyToNull((String) cache.get(key));
+      return NullHandling.emptyToNullIfNeeded((String) cache.get(keyEquivalent));
     }
     finally {
       if (cacheRefKeeper != null && cache != null) {
@@ -129,8 +137,16 @@ public class PollingLookup extends LookupExtractor
   }
 
   @Override
-  public List<String> unapply(final String value)
+  public List<String> unapply(@Nullable final String value)
   {
+    String valueEquivalent = NullHandling.nullToEmptyIfNeeded(value);
+    if (valueEquivalent == null) {
+      // valueEquivalent is null only for SQL Compatible Null Behavior
+      // otherwise null will be replaced with empty string in nullToEmptyIfNeeded above.
+      // null value maps to empty list when SQL Compatible
+      return Collections.emptyList();
+    }
+
     CacheRefKeeper cacheRefKeeper = refOfCacheKeeper.get();
     if (cacheRefKeeper == null) {
       throw new ISE("pollingLookup id [%s] is closed", id);
@@ -139,9 +155,9 @@ public class PollingLookup extends LookupExtractor
     try {
       if (cache == null) {
         // it must've been closed after swapping while I was getting it.  Try again.
-        return this.unapply(value);
+        return this.unapply(valueEquivalent);
       }
-      return cache.getKeys(value);
+      return cache.getKeys(valueEquivalent);
     }
     finally {
       if (cacheRefKeeper != null && cache != null) {

extensions-core/lookups-cached-single/src/main/java/io/druid/server/lookup/jdbc/JdbcDataFetcher.java

@@ -21,8 +21,9 @@ package io.druid.server.lookup.jdbc;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.common.base.Preconditions;
-import com.google.common.base.Strings;
 import com.google.common.collect.Lists;
+
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.StringUtils;
 import io.druid.java.util.common.logger.Logger;
 import io.druid.metadata.MetadataStorageConnectorConfig;
@@ -131,7 +132,7 @@ public class JdbcDataFetcher implements DataFetcher<String, String>
     if (pairs.isEmpty()) {
       return null;
     }
-    return Strings.nullToEmpty(pairs.get(0));
+    return NullHandling.nullToEmptyIfNeeded(pairs.get(0));
   }
 
   @Override

extensions-core/lookups-cached-single/src/test/java/io/druid/server/lookup/LoadingLookupTest.java

@@ -21,6 +21,7 @@ package io.druid.server.lookup;
 
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
+import io.druid.common.config.NullHandling;
 import io.druid.server.lookup.cache.loading.LoadingCache;
 import org.easymock.EasyMock;
 import org.junit.Assert;
@@ -39,16 +40,29 @@ public class LoadingLookupTest
   LoadingLookup loadingLookup = new LoadingLookup(dataFetcher, lookupCache, reverseLookupCache);
 
   @Test
-  public void testApplyEmptyOrNull()
+  public void testApplyEmptyOrNull() throws ExecutionException
   {
-    Assert.assertEquals(null, loadingLookup.apply(null));
+    EasyMock.expect(lookupCache.get(EasyMock.eq(""), EasyMock.anyObject(Callable.class)))
-    Assert.assertEquals(null, loadingLookup.apply(""));
+            .andReturn("empty").atLeastOnce();
+    EasyMock.replay(lookupCache);
+    Assert.assertEquals("empty", loadingLookup.apply(""));
+    if (!NullHandling.sqlCompatible()) {
+      // Nulls and empty strings should have same behavior
+      Assert.assertEquals("empty", loadingLookup.apply(null));
+    } else {
+      Assert.assertNull(loadingLookup.apply(null));
+    }
+    EasyMock.verify(lookupCache);
   }
 
   @Test
   public void testUnapplyNull()
   {
-    Assert.assertEquals(Collections.EMPTY_LIST, loadingLookup.unapply(null));
+    if (NullHandling.sqlCompatible()) {
+      Assert.assertEquals(Collections.emptyList(), loadingLookup.unapply(null));
+    } else {
+      Assert.assertNull(loadingLookup.unapply(null));
+    }
   }
 
   @Test
@@ -88,7 +102,7 @@ public class LoadingLookupTest
             .andThrow(new ExecutionException(null))
             .once();
     EasyMock.replay(lookupCache);
-    Assert.assertEquals(null, loadingLookup.apply("key"));
+    Assert.assertNull(loadingLookup.apply("key"));
     EasyMock.verify(lookupCache);
   }
 
@@ -99,7 +113,7 @@ public class LoadingLookupTest
             .andThrow(new ExecutionException(null))
             .once();
     EasyMock.replay(reverseLookupCache);
-    Assert.assertEquals(Collections.EMPTY_LIST, loadingLookup.unapply("value"));
+    Assert.assertEquals(Collections.emptyList(), loadingLookup.unapply("value"));
     EasyMock.verify(reverseLookupCache);
   }
 

extensions-core/lookups-cached-single/src/test/java/io/druid/server/lookup/PollingLookupTest.java

@@ -21,10 +21,11 @@ package io.druid.server.lookup;
 
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import com.google.common.base.Function;
-import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
+
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.ISE;
 import io.druid.query.lookup.LookupExtractor;
 import io.druid.server.lookup.cache.polling.OffHeapPollingCache;
@@ -190,7 +191,7 @@ public class PollingLookupTest
       public String apply(String input)
       {
         //make sure to rewrite null strings as empty.
-        return Strings.nullToEmpty(input);
+        return NullHandling.nullToEmptyIfNeeded(input);
       }
     }));
   }
@@ -207,7 +208,7 @@ public class PollingLookupTest
     for (Map.Entry<String, String> entry : map.entrySet()) {
       String key = entry.getKey();
       String val = entry.getValue();
-      Assert.assertEquals("non-null check", Strings.emptyToNull(val), lookup.apply(key));
+      Assert.assertEquals("non-null check", NullHandling.emptyToNullIfNeeded(val), lookup.apply(key));
     }
   }
 }

extensions-core/stats/src/test/java/io/druid/query/aggregation/variance/VarianceAggregatorTest.java

@@ -111,7 +111,7 @@ public class VarianceAggregatorTest
         colSelectorFactory
     );
 
-    ByteBuffer buffer = ByteBuffer.wrap(new byte[aggFactory.getMaxIntermediateSize()]);
+    ByteBuffer buffer = ByteBuffer.wrap(new byte[aggFactory.getMaxIntermediateSizeWithNulls()]);
     agg.init(buffer, 0);
 
     assertValues((VarianceAggregatorCollector) agg.get(buffer, 0), 0, 0d, 0d);

indexing-hadoop/src/main/java/io/druid/indexer/InputRowSerde.java

@@ -26,6 +26,7 @@ import com.google.common.io.ByteArrayDataInput;
 import com.google.common.io.ByteArrayDataOutput;
 import com.google.common.io.ByteStreams;
 
+import io.druid.common.config.NullHandling;
 import io.druid.data.input.InputRow;
 import io.druid.data.input.MapBasedInputRow;
 import io.druid.data.input.Rows;
@@ -45,6 +46,7 @@ import io.druid.segment.serde.ComplexMetricSerde;
 import io.druid.segment.serde.ComplexMetrics;
 import org.apache.hadoop.io.WritableUtils;
 
+import javax.annotation.Nullable;
 import java.io.DataInput;
 import java.io.IOException;
 import java.util.ArrayList;
@@ -330,7 +332,10 @@ public class InputRowSerde
           }
 
           String t = aggFactory.getTypeName();
-
+          if (agg.isNull()) {
+            out.writeByte(NullHandling.IS_NULL_BYTE);
+          } else {
+            out.writeByte(NullHandling.IS_NOT_NULL_BYTE);
             if ("float".equals(t)) {
               out.writeFloat(agg.getFloat());
             } else if ("long".equals(t)) {
@@ -345,6 +350,7 @@ public class InputRowSerde
             }
           }
         }
+      }
 
       return new SerializeResult(out.toByteArray(), parseExceptionMessages);
     }
@@ -353,11 +359,14 @@ public class InputRowSerde
     }
   }
 
-  private static void writeBytes(byte[] value, ByteArrayDataOutput out) throws IOException
+  private static void writeBytes(@Nullable byte[] value, ByteArrayDataOutput out) throws IOException
   {
-    WritableUtils.writeVInt(out, value.length);
+    int length = value == null ? -1 : value.length;
+    WritableUtils.writeVInt(out, length);
+    if (value != null) {
       out.write(value, 0, value.length);
     }
+  }
 
   private static void writeString(String value, ByteArrayDataOutput out) throws IOException
   {
@@ -450,6 +459,11 @@ public class InputRowSerde
       for (int i = 0; i < metricSize; i++) {
         String metric = readString(in);
         String type = getType(metric, aggs, i);
+        byte metricNullability = in.readByte();
+        if (metricNullability == NullHandling.IS_NULL_BYTE) {
+          // metric value is null.
+          continue;
+        }
         if ("float".equals(type)) {
           event.put(metric, in.readFloat());
         } else if ("long".equals(type)) {

indexing-hadoop/src/main/java/io/druid/indexer/JobHelper.java

@@ -295,8 +295,8 @@ public class JobHelper
 
   public static void injectDruidProperties(Configuration configuration, List<String> listOfAllowedPrefix)
   {
-    String mapJavaOpts = Strings.nullToEmpty(configuration.get(MRJobConfig.MAP_JAVA_OPTS));
+    String mapJavaOpts = StringUtils.nullToEmptyNonDruidDataString(configuration.get(MRJobConfig.MAP_JAVA_OPTS));
-    String reduceJavaOpts = Strings.nullToEmpty(configuration.get(MRJobConfig.REDUCE_JAVA_OPTS));
+    String reduceJavaOpts = StringUtils.nullToEmptyNonDruidDataString(configuration.get(MRJobConfig.REDUCE_JAVA_OPTS));
 
     for (String propName : System.getProperties().stringPropertyNames()) {
       for (String prefix : listOfAllowedPrefix) {

indexing-hadoop/src/main/java/io/druid/indexer/path/StaticPathSpec.java

@@ -21,11 +21,11 @@ package io.druid.indexer.path;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
-import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Sets;
 import io.druid.indexer.HadoopDruidIndexerConfig;
+import io.druid.java.util.common.StringUtils;
 import io.druid.java.util.common.logger.Logger;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.Path;
@@ -126,7 +126,9 @@ public class StaticPathSpec implements PathSpec
   private static void addInputPath(Job job, Iterable<String> pathStrings, Class<? extends InputFormat> inputFormatClass)
   {
     Configuration conf = job.getConfiguration();
-    StringBuilder inputFormats = new StringBuilder(Strings.nullToEmpty(conf.get(MultipleInputs.DIR_FORMATS)));
+    StringBuilder inputFormats = new StringBuilder(
+        StringUtils.nullToEmptyNonDruidDataString(conf.get(MultipleInputs.DIR_FORMATS))
+    );
 
     String[] paths = Iterables.toArray(pathStrings, String.class);
     for (int i = 0; i < paths.length - 1; i++) {

indexing-hadoop/src/test/java/io/druid/indexer/InputRowSerdeTest.java

@@ -21,6 +21,7 @@ package io.druid.indexer;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Maps;
+import io.druid.common.config.NullHandling;
 import io.druid.data.input.InputRow;
 import io.druid.data.input.MapBasedInputRow;
 import io.druid.data.input.impl.DimensionsSpec;
@@ -83,6 +84,7 @@ public class InputRowSerdeTest
   {
     // Prepare the mocks & set close() call count expectation to 1
     final Aggregator mockedAggregator = EasyMock.createMock(DoubleSumAggregator.class);
+    EasyMock.expect(mockedAggregator.isNull()).andReturn(false).times(1);
     EasyMock.expect(mockedAggregator.getDouble()).andReturn(0d).times(1);
     mockedAggregator.aggregate();
     EasyMock.expectLastCall().times(1);
@@ -90,6 +92,26 @@ public class InputRowSerdeTest
     EasyMock.expectLastCall().times(1);
     EasyMock.replay(mockedAggregator);
 
+    final Aggregator mockedNullAggregator = EasyMock.createMock(DoubleSumAggregator.class);
+    EasyMock.expect(mockedNullAggregator.isNull()).andReturn(true).times(1);
+    mockedNullAggregator.aggregate();
+    EasyMock.expectLastCall().times(1);
+    mockedNullAggregator.close();
+    EasyMock.expectLastCall().times(1);
+    EasyMock.replay(mockedNullAggregator);
+
+    final AggregatorFactory mockedAggregatorFactory = EasyMock.createMock(AggregatorFactory.class);
+    EasyMock.expect(mockedAggregatorFactory.factorize(EasyMock.anyObject(ColumnSelectorFactory.class))).andReturn(mockedAggregator);
+    EasyMock.expect(mockedAggregatorFactory.getTypeName()).andReturn("double").anyTimes();
+    EasyMock.expect(mockedAggregatorFactory.getName()).andReturn("mockedAggregator").anyTimes();
+
+    final AggregatorFactory mockedNullAggregatorFactory = EasyMock.createMock(AggregatorFactory.class);
+    EasyMock.expect(mockedNullAggregatorFactory.factorize(EasyMock.anyObject(ColumnSelectorFactory.class))).andReturn(mockedNullAggregator);
+    EasyMock.expect(mockedNullAggregatorFactory.getName()).andReturn("mockedNullAggregator").anyTimes();
+    EasyMock.expect(mockedNullAggregatorFactory.getTypeName()).andReturn("double").anyTimes();
+
+    EasyMock.replay(mockedAggregatorFactory, mockedNullAggregatorFactory);
+
     InputRow in = new MapBasedInputRow(
         timestamp,
         dims,
@@ -102,13 +124,8 @@ public class InputRowSerdeTest
         new LongSumAggregatorFactory("m2out", "m2"),
         new HyperUniquesAggregatorFactory("m3out", "m3"),
         new LongSumAggregatorFactory("unparseable", "m3"), // Unparseable from String to Long
-        new DoubleSumAggregatorFactory("mockedAggregator", "m4") {
+        mockedAggregatorFactory,
-          @Override
+        mockedNullAggregatorFactory
-          public Aggregator factorize(ColumnSelectorFactory metricFactory)
-          {
-            return mockedAggregator;
-          }
-        }
     };
 
     DimensionsSpec dimensionsSpec = new DimensionsSpec(
@@ -136,13 +153,14 @@ public class InputRowSerdeTest
     Assert.assertEquals(300.1f, out.getRaw("d4"));
     Assert.assertEquals(400.5d, out.getRaw("d5"));
 
-    Assert.assertEquals(0.0f, out.getMetric("agg_non_existing").floatValue(), 0.00001);
+    Assert.assertEquals(NullHandling.defaultDoubleValue(), out.getMetric("agg_non_existing"));
     Assert.assertEquals(5.0f, out.getMetric("m1out").floatValue(), 0.00001);
     Assert.assertEquals(100L, out.getMetric("m2out"));
     Assert.assertEquals(1, ((HyperLogLogCollector) out.getRaw("m3out")).estimateCardinality(), 0.001);
     Assert.assertEquals(0L, out.getMetric("unparseable"));
 
     EasyMock.verify(mockedAggregator);
+    EasyMock.verify(mockedNullAggregator);
   }
 
   @Test

indexing-service/src/test/java/io/druid/indexing/common/task/AppenderatorDriverRealtimeIndexTaskTest.java

@@ -31,6 +31,7 @@ import com.google.common.util.concurrent.ListeningExecutorService;
 import com.google.common.util.concurrent.MoreExecutors;
 import io.druid.client.cache.CacheConfig;
 import io.druid.client.cache.MapCache;
+import io.druid.common.config.NullHandling;
 import io.druid.data.input.Firehose;
 import io.druid.data.input.FirehoseFactory;
 import io.druid.data.input.InputRow;
@@ -130,6 +131,7 @@ import io.druid.server.security.AuthTestUtils;
 import io.druid.timeline.DataSegment;
 import io.druid.timeline.partition.LinearShardSpec;
 import io.druid.timeline.partition.NumberedShardSpec;
+import io.druid.utils.Runnables;
 import org.apache.commons.io.FileUtils;
 import org.easymock.EasyMock;
 import org.joda.time.DateTime;
@@ -142,6 +144,7 @@ import org.junit.Test;
 import org.junit.rules.ExpectedException;
 import org.junit.rules.TemporaryFolder;
 
+import javax.annotation.Nullable;
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Files;
@@ -223,7 +226,7 @@ public class AppenderatorDriverRealtimeIndexTaskTest
     @Override
     public Runnable commit()
     {
-      return () -> {};
+      return Runnables.getNoopRunnable();
     }
 
     @Override
@@ -331,7 +334,8 @@ public class AppenderatorDriverRealtimeIndexTaskTest
 
     // handoff would timeout, resulting in exception
     TaskStatus status = statusFuture.get();
-    Assert.assertTrue(status.getErrorMsg().contains("java.util.concurrent.TimeoutException: Timeout waiting for task."));
+    Assert.assertTrue(status.getErrorMsg()
+                            .contains("java.util.concurrent.TimeoutException: Timeout waiting for task."));
   }
 
   @Test(timeout = 60_000L)
@@ -367,8 +371,8 @@ public class AppenderatorDriverRealtimeIndexTaskTest
     Assert.assertEquals(0, task.getRowIngestionMeters().getUnparseable());
 
     // Do some queries.
-    Assert.assertEquals(2, sumMetric(task, null, "rows"));
+    Assert.assertEquals(2, sumMetric(task, null, "rows").longValue());
-    Assert.assertEquals(3, sumMetric(task, null, "met1"));
+    Assert.assertEquals(3, sumMetric(task, null, "met1").longValue());
 
     awaitHandoffs();
 
@@ -429,8 +433,8 @@ public class AppenderatorDriverRealtimeIndexTaskTest
     Assert.assertEquals(0, task.getRowIngestionMeters().getUnparseable());
 
     // Do some queries.
-    Assert.assertEquals(2, sumMetric(task, null, "rows"));
+    Assert.assertEquals(2, sumMetric(task, null, "rows").longValue());
-    Assert.assertEquals(3, sumMetric(task, null, "met1"));
+    Assert.assertEquals(3, sumMetric(task, null, "met1").longValue());
 
     awaitHandoffs();
 
@@ -494,8 +498,8 @@ public class AppenderatorDriverRealtimeIndexTaskTest
     Assert.assertEquals(0, task.getRowIngestionMeters().getUnparseable());
 
     // Do some queries.
-    Assert.assertEquals(2000, sumMetric(task, null, "rows"));
+    Assert.assertEquals(2000, sumMetric(task, null, "rows").longValue());
-    Assert.assertEquals(2000, sumMetric(task, null, "met1"));
+    Assert.assertEquals(2000, sumMetric(task, null, "met1").longValue());
 
     awaitHandoffs();
 
@@ -562,10 +566,14 @@ public class AppenderatorDriverRealtimeIndexTaskTest
     Assert.assertEquals(0, task.getRowIngestionMeters().getUnparseable());
 
     // Do some queries.
-    Assert.assertEquals(2, sumMetric(task, null, "rows"));
+    Assert.assertEquals(2, sumMetric(task, null, "rows").longValue());
-    Assert.assertEquals(2, sumMetric(task, new SelectorDimFilter("dim1t", "foofoo", null), "rows"));
+    Assert.assertEquals(2, sumMetric(task, new SelectorDimFilter("dim1t", "foofoo", null), "rows").longValue());
-    Assert.assertEquals(0, sumMetric(task, new SelectorDimFilter("dim1t", "barbar", null), "rows"));
+    if (NullHandling.replaceWithDefault()) {
-    Assert.assertEquals(3, sumMetric(task, null, "met1"));
+      Assert.assertEquals(0, sumMetric(task, new SelectorDimFilter("dim1t", "barbar", null), "metric1").longValue());
+    } else {
+      Assert.assertNull(sumMetric(task, new SelectorDimFilter("dim1t", "barbar", null), "metric1"));
+    }
+    Assert.assertEquals(3, sumMetric(task, null, "met1").longValue());
 
     awaitHandoffs();
 
@@ -620,7 +628,8 @@ public class AppenderatorDriverRealtimeIndexTaskTest
 
     // Wait for the task to finish.
     TaskStatus status = statusFuture.get();
-    Assert.assertTrue(status.getErrorMsg().contains("java.lang.RuntimeException: Max parse exceptions exceeded, terminating task..."));
+    Assert.assertTrue(status.getErrorMsg()
+                            .contains("java.lang.RuntimeException: Max parse exceptions exceeded, terminating task..."));
 
     IngestionStatsAndErrorsTaskReportData reportData = getTaskReportData();
 
@@ -639,7 +648,15 @@ public class AppenderatorDriverRealtimeIndexTaskTest
   {
     expectPublishedSegments(1);
 
-    final AppenderatorDriverRealtimeIndexTask task = makeRealtimeTask(null, TransformSpec.NONE, false, 0, true, null, 1);
+    final AppenderatorDriverRealtimeIndexTask task = makeRealtimeTask(
+        null,
+        TransformSpec.NONE,
+        false,
+        0,
+        true,
+        null,
+        1
+    );
     final ListenableFuture<TaskStatus> statusFuture = runTask(task);
 
     // Wait for firehose to show up, it starts off null.
@@ -683,8 +700,8 @@ public class AppenderatorDriverRealtimeIndexTaskTest
     Assert.assertEquals(2, task.getRowIngestionMeters().getUnparseable());
 
     // Do some queries.
-    Assert.assertEquals(3, sumMetric(task, null, "rows"));
+    Assert.assertEquals(3, sumMetric(task, null, "rows").longValue());
-    Assert.assertEquals(3, sumMetric(task, null, "met1"));
+    Assert.assertEquals(3, sumMetric(task, null, "met1").longValue());
 
     awaitHandoffs();
 
@@ -750,7 +767,18 @@ public class AppenderatorDriverRealtimeIndexTaskTest
             ImmutableMap.of("t", 1521251960729L, "dim1", "foo", "met1", "foo"),
 
             // Bad long dim- will count as processed, but bad dims will get default values
-            ImmutableMap.of("t", 1521251960729L, "dim1", "foo", "dimLong", "notnumber", "dimFloat", "notnumber", "met1", "foo"),
+            ImmutableMap.of(
+                "t",
+                1521251960729L,
+                "dim1",
+                "foo",
+                "dimLong",
+                "notnumber",
+                "dimFloat",
+                "notnumber",
+                "met1",
+                "foo"
+            ),
 
             // Bad row- will be unparseable.
             ImmutableMap.of("dim1", "foo", "met1", 2.0, FAIL_DIM, "x"),
@@ -775,8 +803,8 @@ public class AppenderatorDriverRealtimeIndexTaskTest
     Assert.assertEquals(2, task.getRowIngestionMeters().getUnparseable());
 
     // Do some queries.
-    Assert.assertEquals(4, sumMetric(task, null, "rows"));
+    Assert.assertEquals(4, sumMetric(task, null, "rows").longValue());
-    Assert.assertEquals(3, sumMetric(task, null, "met1"));
+    Assert.assertEquals(3, sumMetric(task, null, "met1").longValue());
 
     awaitHandoffs();
 
@@ -852,7 +880,18 @@ public class AppenderatorDriverRealtimeIndexTaskTest
             ImmutableMap.of("t", 1521251960729L, "dim1", "foo", "met1", "foo"),
 
             // Bad long dim- will count as processed, but bad dims will get default values
-            ImmutableMap.of("t", 1521251960729L, "dim1", "foo", "dimLong", "notnumber", "dimFloat", "notnumber", "met1", "foo"),
+            ImmutableMap.of(
+                "t",
+                1521251960729L,
+                "dim1",
+                "foo",
+                "dimLong",
+                "notnumber",
+                "dimFloat",
+                "notnumber",
+                "met1",
+                "foo"
+            ),
 
             // Bad row- will be unparseable.
             ImmutableMap.of("dim1", "foo", "met1", 2.0, FAIL_DIM, "x"),
@@ -943,7 +982,7 @@ public class AppenderatorDriverRealtimeIndexTaskTest
       }
 
       // Do a query, at this point the previous data should be loaded.
-      Assert.assertEquals(1, sumMetric(task2, null, "rows"));
+      Assert.assertEquals(1, sumMetric(task2, null, "rows").longValue());
 
       final TestFirehose firehose = (TestFirehose) task2.getFirehose();
 
@@ -961,7 +1000,7 @@ public class AppenderatorDriverRealtimeIndexTaskTest
       publishedSegment = Iterables.getOnlyElement(publishedSegments);
 
       // Do a query.
-      Assert.assertEquals(2, sumMetric(task2, null, "rows"));
+      Assert.assertEquals(2, sumMetric(task2, null, "rows").longValue());
 
       awaitHandoffs();
 
@@ -1018,7 +1057,7 @@ public class AppenderatorDriverRealtimeIndexTaskTest
       publishedSegment = Iterables.getOnlyElement(publishedSegments);
 
       // Do a query.
-      Assert.assertEquals(1, sumMetric(task1, null, "rows"));
+      Assert.assertEquals(1, sumMetric(task1, null, "rows").longValue());
 
       // Trigger graceful shutdown.
       task1.stopGracefully();
@@ -1137,7 +1176,8 @@ public class AppenderatorDriverRealtimeIndexTaskTest
 
       IngestionStatsAndErrorsTaskReportData reportData = getTaskReportData();
       Assert.assertEquals(expectedMetrics, reportData.getRowStats());
-      Assert.assertTrue(status.getErrorMsg().contains("java.lang.IllegalArgumentException\n\tat java.nio.Buffer.position"));
+      Assert.assertTrue(status.getErrorMsg()
+                              .contains("java.lang.IllegalArgumentException\n\tat java.nio.Buffer.position"));
     }
   }
 
@@ -1466,7 +1506,8 @@ public class AppenderatorDriverRealtimeIndexTaskTest
     );
   }
 
-  public long sumMetric(final Task task, final DimFilter filter, final String metric)
+  @Nullable
+  public Long sumMetric(final Task task, final DimFilter filter, final String metric)
   {
     // Do a query.
     TimeseriesQuery query = Druids.newTimeseriesQueryBuilder()
@@ -1482,7 +1523,12 @@ public class AppenderatorDriverRealtimeIndexTaskTest
 
     List<Result<TimeseriesResultValue>> results =
         task.getQueryRunner(query).run(QueryPlus.wrap(query), ImmutableMap.of()).toList();
-    return results.isEmpty() ? 0 : results.get(0).getValue().getLongMetric(metric);
+
+    if (results.isEmpty()) {
+      return 0L;
+    } else {
+      return results.get(0).getValue().getLongMetric(metric);
+    }
   }
 
   private IngestionStatsAndErrorsTaskReportData getTaskReportData() throws IOException

indexing-service/src/test/java/io/druid/indexing/common/task/RealtimeIndexTaskTest.java

@@ -32,6 +32,7 @@ import com.google.common.util.concurrent.ListeningExecutorService;
 import com.google.common.util.concurrent.MoreExecutors;
 import io.druid.client.cache.CacheConfig;
 import io.druid.client.cache.MapCache;
+import io.druid.common.config.NullHandling;
 import io.druid.data.input.Firehose;
 import io.druid.data.input.FirehoseFactory;
 import io.druid.data.input.InputRow;
@@ -118,6 +119,7 @@ import io.druid.server.DruidNode;
 import io.druid.server.coordination.DataSegmentServerAnnouncer;
 import io.druid.server.coordination.ServerType;
 import io.druid.timeline.DataSegment;
+import io.druid.utils.Runnables;
 import org.easymock.EasyMock;
 import org.hamcrest.CoreMatchers;
 import org.joda.time.DateTime;
@@ -131,6 +133,7 @@ import org.junit.internal.matchers.ThrowableMessageMatcher;
 import org.junit.rules.ExpectedException;
 import org.junit.rules.TemporaryFolder;
 
+import javax.annotation.Nullable;
 import java.io.File;
 import java.nio.file.Files;
 import java.util.Arrays;
@@ -204,7 +207,7 @@ public class RealtimeIndexTaskTest
     @Override
     public Runnable commit()
     {
-      return () -> {};
+      return Runnables.getNoopRunnable();
     }
 
     @Override
@@ -350,8 +353,8 @@ public class RealtimeIndexTaskTest
     Assert.assertEquals(0, task.getMetrics().unparseable());
 
     // Do some queries.
-    Assert.assertEquals(2, sumMetric(task, null, "rows"));
+    Assert.assertEquals(2, sumMetric(task, null, "rows").longValue());
-    Assert.assertEquals(3, sumMetric(task, null, "met1"));
+    Assert.assertEquals(3, sumMetric(task, null, "met1").longValue());
 
     // Simulate handoff.
     for (Map.Entry<SegmentDescriptor, Pair<Executor, Runnable>> entry : handOffCallbacks.entrySet()) {
@@ -419,10 +422,15 @@ public class RealtimeIndexTaskTest
     Assert.assertEquals(0, task.getMetrics().unparseable());
 
     // Do some queries.
-    Assert.assertEquals(1, sumMetric(task, null, "rows"));
+    Assert.assertEquals(1, sumMetric(task, null, "rows").longValue());
-    Assert.assertEquals(1, sumMetric(task, new SelectorDimFilter("dim1t", "foofoo", null), "rows"));
+    Assert.assertEquals(1, sumMetric(task, new SelectorDimFilter("dim1t", "foofoo", null), "rows").longValue());
-    Assert.assertEquals(0, sumMetric(task, new SelectorDimFilter("dim1t", "barbar", null), "rows"));
+    if (NullHandling.replaceWithDefault()) {
-    Assert.assertEquals(1, sumMetric(task, null, "met1"));
+      Assert.assertEquals(0, sumMetric(task, new SelectorDimFilter("dim1t", "barbar", null), "rows").longValue());
+    } else {
+      Assert.assertNull(sumMetric(task, new SelectorDimFilter("dim1t", "barbar", null), "rows"));
+
+    }
+    Assert.assertEquals(1, sumMetric(task, null, "met1").longValue());
 
     // Simulate handoff.
     for (Map.Entry<SegmentDescriptor, Pair<Executor, Runnable>> entry : handOffCallbacks.entrySet()) {
@@ -537,8 +545,8 @@ public class RealtimeIndexTaskTest
     Assert.assertEquals(2, task.getMetrics().unparseable());
 
     // Do some queries.
-    Assert.assertEquals(3, sumMetric(task, null, "rows"));
+    Assert.assertEquals(3, sumMetric(task, null, "rows").longValue());
-    Assert.assertEquals(3, sumMetric(task, null, "met1"));
+    Assert.assertEquals(3, sumMetric(task, null, "met1").longValue());
 
     // Simulate handoff.
     for (Map.Entry<SegmentDescriptor, Pair<Executor, Runnable>> entry : handOffCallbacks.entrySet()) {
@@ -610,7 +618,7 @@ public class RealtimeIndexTaskTest
       }
 
       // Do a query, at this point the previous data should be loaded.
-      Assert.assertEquals(1, sumMetric(task2, null, "rows"));
+      Assert.assertEquals(1, sumMetric(task2, null, "rows").longValue());
 
       final TestFirehose firehose = (TestFirehose) task2.getFirehose();
 
@@ -631,7 +639,7 @@ public class RealtimeIndexTaskTest
       publishedSegment = Iterables.getOnlyElement(mdc.getPublished());
 
       // Do a query.
-      Assert.assertEquals(2, sumMetric(task2, null, "rows"));
+      Assert.assertEquals(2, sumMetric(task2, null, "rows").longValue());
 
       // Simulate handoff.
       for (Map.Entry<SegmentDescriptor, Pair<Executor, Runnable>> entry : handOffCallbacks.entrySet()) {
@@ -692,7 +700,7 @@ public class RealtimeIndexTaskTest
       publishedSegment = Iterables.getOnlyElement(mdc.getPublished());
 
       // Do a query.
-      Assert.assertEquals(1, sumMetric(task1, null, "rows"));
+      Assert.assertEquals(1, sumMetric(task1, null, "rows").longValue());
 
       // Trigger graceful shutdown.
       task1.stopGracefully();
@@ -1080,7 +1088,8 @@ public class RealtimeIndexTaskTest
     return toolboxFactory.build(task);
   }
 
-  public long sumMetric(final Task task, final DimFilter filter, final String metric)
+  @Nullable
+  public Long sumMetric(final Task task, final DimFilter filter, final String metric)
   {
     // Do a query.
     TimeseriesQuery query = Druids.newTimeseriesQueryBuilder()
@@ -1096,6 +1105,10 @@ public class RealtimeIndexTaskTest
 
     List<Result<TimeseriesResultValue>> results =
         task.getQueryRunner(query).run(QueryPlus.wrap(query), ImmutableMap.of()).toList();
-    return results.isEmpty() ? 0 : results.get(0).getValue().getLongMetric(metric);
+    if (results.isEmpty()) {
+      return 0L;
+    } else {
+      return results.get(0).getValue().getLongMetric(metric);
+    }
   }
 }

java-util/pom.xml

@@ -53,6 +53,10 @@
             <groupId>org.skife.config</groupId>
             <artifactId>config-magic</artifactId>
         </dependency>
+        <dependency>
+            <groupId>com.google.inject</groupId>
+            <artifactId>guice</artifactId>
+        </dependency>
         <dependency>
             <groupId>com.google.guava</groupId>
             <artifactId>guava</artifactId>

java-util/src/main/java/io/druid/common/config/NullHandling.java

@@ -41,18 +41,22 @@ public class NullHandling
   public static final Double ZERO_DOUBLE = 0.0d;
   public static final Float ZERO_FLOAT = 0.0f;
   public static final Long ZERO_LONG = 0L;
+  public static final byte IS_NULL_BYTE = (byte) 1;
+  public static final byte IS_NOT_NULL_BYTE = (byte) 0;
 
   /**
    * INSTANCE is injected using static injection to avoid adding JacksonInject annotations all over the code.
    * See io.druid.guice.NullHandlingModule for details.
    * It does not take effect in all unit tests since we don't use Guice Injection.
-   * For tests default system property is supposed to be used only in tests
    */
   @Inject
   private static NullValueHandlingConfig INSTANCE = new NullValueHandlingConfig(
       Boolean.valueOf(System.getProperty(NULL_HANDLING_CONFIG_STRING, "true"))
   );
 
+  /**
+   * whether nulls should be replaced with default value.
+   */
   public static boolean replaceWithDefault()
   {
     return INSTANCE.isUseDefaultValuesForNull();

java-util/src/main/java/io/druid/java/util/common/StringUtils.java

@@ -19,6 +19,7 @@
 
 package io.druid.java.util.common;
 
+import com.google.common.base.Strings;
 import com.google.common.base.Throwables;
 
 import javax.annotation.Nullable;
@@ -172,4 +173,36 @@ public class StringUtils
     }
     return sb.toString();
   }
+
+  /**
+   * Returns the given string if it is non-null; the empty string otherwise.
+   * This method should only be used at places where null to empty conversion is
+   * irrelevant to null handling of the data.
+   *
+   * @param string the string to test and possibly return
+   * @return {@code string} itself if it is non-null; {@code ""} if it is null
+   */
+  public static String nullToEmptyNonDruidDataString(@Nullable String string)
+  {
+    //CHECKSTYLE.OFF: Regexp
+    return Strings.nullToEmpty(string);
+    //CHECKSTYLE.ON: Regexp
+  }
+
+  /**
+   * Returns the given string if it is nonempty; {@code null} otherwise.
+   * This method should only be used at places where null to empty conversion is
+   * irrelevant to null handling of the data.
+   *
+   * @param string the string to test and possibly return
+   * @return {@code string} itself if it is nonempty; {@code null} if it is
+   *     empty or null
+   */
+  @Nullable
+  public static String emptyToNullNonDruidDataString(@Nullable String string)
+  {
+    //CHECKSTYLE.OFF: Regexp
+    return Strings.emptyToNull(string);
+    //CHECKSTYLE.ON: Regexp
+  }
 }

java-util/src/main/java/io/druid/java/util/common/parsers/ParserUtils.java

@@ -21,8 +21,8 @@ package io.druid.java.util.common.parsers;
 
 import com.google.common.base.Function;
 import com.google.common.base.Splitter;
-import com.google.common.base.Strings;
 import com.google.common.collect.Sets;
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.StringUtils;
 import org.joda.time.DateTimeZone;
 
@@ -60,10 +60,10 @@ public class ParserUtils
     return (input) -> {
       if (input != null && input.contains(listDelimiter)) {
         return StreamSupport.stream(listSplitter.split(input).spliterator(), false)
-                            .map(Strings::emptyToNull)
+                            .map(NullHandling::emptyToNullIfNeeded)
                             .collect(Collectors.toList());
       } else {
-        return Strings.emptyToNull(input);
+        return NullHandling.emptyToNullIfNeeded(input);
       }
     };
   }

java-util/src/main/java/io/druid/java/util/http/client/NettyHttpClient.java

@@ -20,7 +20,6 @@
 package io.druid.java.util.http.client;
 
 import com.google.common.base.Preconditions;
-import com.google.common.base.Strings;
 import com.google.common.collect.Multimap;
 import com.google.common.util.concurrent.Futures;
 import com.google.common.util.concurrent.ListenableFuture;
@@ -140,8 +139,7 @@ public class NettyHttpClient extends AbstractHttpClient
     } else {
       channel = channelFuture.getChannel();
     }
-
+    final String urlFile = StringUtils.nullToEmptyNonDruidDataString(url.getFile());
-    final String urlFile = Strings.nullToEmpty(url.getFile());
     final HttpRequest httpRequest = new DefaultHttpRequest(
         HttpVersion.HTTP_1_1,
         method,

processing/src/main/java/io/druid/guice/GuiceInjectors.java

@@ -41,6 +41,7 @@ public class GuiceInjectors
         new JacksonModule(),
         new PropertiesModule(Arrays.asList("common.runtime.properties", "runtime.properties")),
         new ConfigModule(),
+        new NullHandlingModule(),
         binder -> {
           binder.bind(DruidSecondaryModule.class);
           JsonConfigProvider.bind(binder, "druid.extensions", ExtensionsConfig.class);

processing/src/main/java/io/druid/guice/NullHandlingModule.java

@@ -0,0 +1,38 @@
+/*
+ * 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 io.druid.guice;
+
+import com.google.inject.Binder;
+import com.google.inject.Module;
+import io.druid.common.config.NullHandling;
+import io.druid.common.config.NullValueHandlingConfig;
+
+/**
+ */
+public class NullHandlingModule implements Module
+{
+  @Override
+  public void configure(Binder binder)
+  {
+    JsonConfigProvider.bind(binder, "druid.generic", NullValueHandlingConfig.class);
+    binder.requestStaticInjection(NullHandling.class);
+    binder.requestStaticInjection(NullHandling.class);
+  }
+}

processing/src/main/java/io/druid/query/DefaultQueryMetrics.java

@@ -21,11 +21,11 @@ package io.druid.query;
 
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.ObjectMapper;
-import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableMap;
+import io.druid.collections.bitmap.BitmapFactory;
+import io.druid.java.util.common.StringUtils;
 import io.druid.java.util.emitter.service.ServiceEmitter;
 import io.druid.java.util.emitter.service.ServiceMetricEvent;
-import io.druid.collections.bitmap.BitmapFactory;
 import io.druid.query.filter.Filter;
 import org.joda.time.Interval;
 
@@ -118,7 +118,7 @@ public class DefaultQueryMetrics<QueryType extends Query<?>> implements QueryMet
   @Override
   public void queryId(QueryType query)
   {
-    setDimension(DruidMetrics.ID, Strings.nullToEmpty(query.getId()));
+    setDimension(DruidMetrics.ID, StringUtils.nullToEmptyNonDruidDataString(query.getId()));
   }
 
   @Override

processing/src/main/java/io/druid/query/aggregation/AggregateCombiner.java

@@ -19,6 +19,7 @@
 
 package io.druid.query.aggregation;
 
+import io.druid.guice.annotations.ExtensionPoint;
 import io.druid.query.monomorphicprocessing.RuntimeShapeInspector;
 import io.druid.segment.ColumnValueSelector;
 
@@ -39,6 +40,7 @@ import io.druid.segment.ColumnValueSelector;
  * @see DoubleAggregateCombiner
  * @see ObjectAggregateCombiner
  */
+@ExtensionPoint
 public interface AggregateCombiner<T> extends ColumnValueSelector<T>
 {
   /**

processing/src/main/java/io/druid/query/aggregation/AggregatorFactory.java

@@ -37,6 +37,8 @@ import java.util.Map;
  * AggregatorFactory is a strategy (in the terms of Design Patterns) that represents column aggregation, e. g. min,
  * max, sum of metric columns, or cardinality of dimension columns (see {@link
  * io.druid.query.aggregation.cardinality.CardinalityAggregatorFactory}).
+ * Implementations of {@link AggregatorFactory} which need to Support Nullable Aggregations are encouraged
+ * to extend {@link NullableAggregatorFactory}.
  */
 @ExtensionPoint
 public abstract class AggregatorFactory implements Cacheable
@@ -60,7 +62,8 @@ public abstract class AggregatorFactory implements Cacheable
    *
    * @return an object representing the combination of lhs and rhs, this can be a new object or a mutation of the inputs
    */
-  public abstract Object combine(Object lhs, Object rhs);
+  @Nullable
+  public abstract Object combine(@Nullable Object lhs, @Nullable Object rhs);
 
   /**
    * Creates an AggregateCombiner to fold rollup aggregation results from serveral "rows" of different indexes during
@@ -76,6 +79,20 @@ public abstract class AggregatorFactory implements Cacheable
     throw new UOE("[%s] does not implement makeAggregateCombiner()", this.getClass().getName());
   }
 
+  /**
+   * Creates an {@link AggregateCombiner} which supports nullability.
+   * Implementations of {@link AggregatorFactory} which need to Support Nullable Aggregations are encouraged
+   * to extend {@link NullableAggregatorFactory} instead of overriding this method.
+   * Default implementation calls {@link #makeAggregateCombiner()} for backwards compatibility.
+   *
+   * @see AggregateCombiner
+   * @see NullableAggregatorFactory
+   */
+  public AggregateCombiner makeNullableAggregateCombiner()
+  {
+    return makeAggregateCombiner();
+  }
+
   /**
    * Returns an AggregatorFactory that can be used to combine the output of aggregators from this factory.  This
    * generally amounts to simply creating a new factory that is the same as the current except with its input
@@ -127,7 +144,8 @@ public abstract class AggregatorFactory implements Cacheable
    *
    * @return the finalized value that should be returned for the initial query
    */
-  public abstract Object finalizeComputation(Object object);
+  @Nullable
+  public abstract Object finalizeComputation(@Nullable Object object);
 
   public abstract String getName();
 
@@ -142,6 +160,19 @@ public abstract class AggregatorFactory implements Cacheable
    */
   public abstract int getMaxIntermediateSize();
 
+  /**
+   * Returns the maximum size that this aggregator will require in bytes for intermediate storage of results.
+   * Implementations of {@link AggregatorFactory} which need to Support Nullable Aggregations are encouraged
+   * to extend {@link NullableAggregatorFactory} instead of overriding this method.
+   * Default implementation calls {@link #makeAggregateCombiner()} for backwards compatibility.
+   *
+   * @return the maximum number of bytes that an aggregator of this type will require for intermediate result storage.
+   */
+  public int getMaxIntermediateSizeWithNulls()
+  {
+    return getMaxIntermediateSize();
+  }
+
   /**
    * Return a potentially optimized form of this AggregatorFactory for per-segment queries.
    */

processing/src/main/java/io/druid/query/aggregation/AggregatorUtil.java

@@ -174,8 +174,10 @@ public class AggregatorUtil
         @Override
         public float getFloat()
         {
+          // Although baseSelector.getObject is nullable
+          // exprEval returned from Expression selectors is never null.
           final ExprEval exprEval = baseSelector.getObject();
-          return exprEval.isNull() ? nullValue : (float) exprEval.asDouble();
+          return exprEval.isNumericNull() ? nullValue : (float) exprEval.asDouble();
         }
 
         @Override
@@ -188,7 +190,7 @@ public class AggregatorUtil
         public boolean isNull()
         {
           final ExprEval exprEval = baseSelector.getObject();
-          return exprEval.isNull();
+          return exprEval == null || exprEval.isNumericNull();
         }
       }
       return new ExpressionFloatColumnSelector();
@@ -216,7 +218,7 @@ public class AggregatorUtil
         public long getLong()
         {
           final ExprEval exprEval = baseSelector.getObject();
-          return exprEval.isNull() ? nullValue : exprEval.asLong();
+          return exprEval.isNumericNull() ? nullValue : exprEval.asLong();
         }
 
         @Override
@@ -229,7 +231,7 @@ public class AggregatorUtil
         public boolean isNull()
         {
           final ExprEval exprEval = baseSelector.getObject();
-          return exprEval.isNull();
+          return exprEval == null || exprEval.isNumericNull();
         }
       }
       return new ExpressionLongColumnSelector();
@@ -257,7 +259,7 @@ public class AggregatorUtil
         public double getDouble()
         {
           final ExprEval exprEval = baseSelector.getObject();
-          return exprEval.isNull() ? nullValue : exprEval.asDouble();
+          return exprEval.isNumericNull() ? nullValue : exprEval.asDouble();
         }
 
         @Override
@@ -270,7 +272,7 @@ public class AggregatorUtil
         public boolean isNull()
         {
           final ExprEval exprEval = baseSelector.getObject();
-          return exprEval.isNull();
+          return exprEval == null || exprEval.isNumericNull();
         }
       }
       return new ExpressionDoubleColumnSelector();

processing/src/main/java/io/druid/query/aggregation/BufferAggregator.java

@@ -44,7 +44,7 @@ public interface BufferAggregator extends HotLoopCallee
    *
    * <b>Implementations must not change the position, limit or mark of the given buffer</b>
    *
-   * This method must not exceed the number of bytes returned by {@link AggregatorFactory#getMaxIntermediateSize()}
+   * This method must not exceed the number of bytes returned by {@link AggregatorFactory#getMaxIntermediateSizeWithNulls}
    * in the corresponding {@link AggregatorFactory}
    *
    * @param buf byte buffer to initialize

processing/src/main/java/io/druid/query/aggregation/DoubleMaxAggregatorFactory.java

@@ -24,8 +24,10 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import io.druid.java.util.common.StringUtils;
 import io.druid.math.expr.ExprMacroTable;
+import io.druid.segment.BaseDoubleColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.List;
@@ -51,20 +53,39 @@ public class DoubleMaxAggregatorFactory extends SimpleDoubleAggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected BaseDoubleColumnValueSelector selector(ColumnSelectorFactory metricFactory)
   {
-    return new DoubleMaxAggregator(getDoubleColumnSelector(metricFactory, Double.NEGATIVE_INFINITY));
+    return getDoubleColumnSelector(
+        metricFactory,
+        Double.NEGATIVE_INFINITY
+    );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  protected Aggregator factorize(ColumnSelectorFactory metricFactory, BaseDoubleColumnValueSelector selector)
   {
-    return new DoubleMaxBufferAggregator(getDoubleColumnSelector(metricFactory, Double.NEGATIVE_INFINITY));
+    return new DoubleMaxAggregator(selector);
   }
 
   @Override
-  public Object combine(Object lhs, Object rhs)
+  protected BufferAggregator factorizeBuffered(
+      ColumnSelectorFactory metricFactory,
+      BaseDoubleColumnValueSelector selector
+  )
   {
+    return new DoubleMaxBufferAggregator(selector);
+  }
+
+  @Override
+  @Nullable
+  public Object combine(@Nullable Object lhs, @Nullable Object rhs)
+  {
+    if (rhs == null) {
+      return lhs;
+    }
+    if (lhs == null) {
+      return rhs;
+    }
     return DoubleMaxAggregator.combineValues(lhs, rhs);
   }
 

processing/src/main/java/io/druid/query/aggregation/DoubleMinAggregatorFactory.java

@@ -24,8 +24,10 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import io.druid.java.util.common.StringUtils;
 import io.druid.math.expr.ExprMacroTable;
+import io.druid.segment.BaseDoubleColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.List;
@@ -51,20 +53,39 @@ public class DoubleMinAggregatorFactory extends SimpleDoubleAggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected BaseDoubleColumnValueSelector selector(ColumnSelectorFactory metricFactory)
   {
-    return new DoubleMinAggregator(getDoubleColumnSelector(metricFactory, Double.POSITIVE_INFINITY));
+    return getDoubleColumnSelector(
+        metricFactory,
+        Double.POSITIVE_INFINITY
+    );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  protected Aggregator factorize(ColumnSelectorFactory metricFactory, BaseDoubleColumnValueSelector selector)
   {
-    return new DoubleMinBufferAggregator(getDoubleColumnSelector(metricFactory, Double.POSITIVE_INFINITY));
+    return new DoubleMinAggregator(selector);
   }
 
   @Override
-  public Object combine(Object lhs, Object rhs)
+  protected BufferAggregator factorizeBuffered(
+      ColumnSelectorFactory metricFactory,
+      BaseDoubleColumnValueSelector selector
+  )
   {
+    return new DoubleMinBufferAggregator(selector);
+  }
+
+  @Override
+  @Nullable
+  public Object combine(@Nullable Object lhs, @Nullable Object rhs)
+  {
+    if (rhs == null) {
+      return lhs;
+    }
+    if (lhs == null) {
+      return rhs;
+    }
     return DoubleMinAggregator.combineValues(lhs, rhs);
   }
 

processing/src/main/java/io/druid/query/aggregation/DoubleSumAggregatorFactory.java

@@ -24,8 +24,10 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import io.druid.java.util.common.StringUtils;
 import io.druid.math.expr.ExprMacroTable;
+import io.druid.segment.BaseDoubleColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.List;
@@ -51,20 +53,39 @@ public class DoubleSumAggregatorFactory extends SimpleDoubleAggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected BaseDoubleColumnValueSelector selector(ColumnSelectorFactory metricFactory)
   {
-    return new DoubleSumAggregator(getDoubleColumnSelector(metricFactory, 0.0));
+    return getDoubleColumnSelector(
+        metricFactory,
+        0.0d
+    );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  protected Aggregator factorize(ColumnSelectorFactory metricFactory, BaseDoubleColumnValueSelector selector)
   {
-    return new DoubleSumBufferAggregator(getDoubleColumnSelector(metricFactory, 0.0));
+    return new DoubleSumAggregator(selector);
   }
 
   @Override
-  public Object combine(Object lhs, Object rhs)
+  protected BufferAggregator factorizeBuffered(
+      ColumnSelectorFactory metricFactory,
+      BaseDoubleColumnValueSelector selector
+  )
   {
+    return new DoubleSumBufferAggregator(selector);
+  }
+
+  @Override
+  @Nullable
+  public Object combine(@Nullable Object lhs, @Nullable Object rhs)
+  {
+    if (rhs == null) {
+      return lhs;
+    }
+    if (lhs == null) {
+      return rhs;
+    }
     return DoubleSumAggregator.combineValues(lhs, rhs);
   }
 

processing/src/main/java/io/druid/query/aggregation/FilteredAggregatorFactory.java

@@ -142,7 +142,7 @@ public class FilteredAggregatorFactory extends AggregatorFactory
   @Override
   public int getMaxIntermediateSize()
   {
-    return delegate.getMaxIntermediateSize();
+    return delegate.getMaxIntermediateSizeWithNulls();
   }
 
   @Override

processing/src/main/java/io/druid/query/aggregation/FloatMaxAggregatorFactory.java

@@ -24,8 +24,10 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import io.druid.java.util.common.StringUtils;
 import io.druid.math.expr.ExprMacroTable;
+import io.druid.segment.BaseFloatColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.List;
@@ -51,20 +53,39 @@ public class FloatMaxAggregatorFactory extends SimpleFloatAggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected BaseFloatColumnValueSelector selector(ColumnSelectorFactory metricFactory)
   {
-    return new FloatMaxAggregator(getFloatColumnSelector(metricFactory, Float.NEGATIVE_INFINITY));
+    return getFloatColumnSelector(
+        metricFactory,
+        Float.NEGATIVE_INFINITY
+    );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  protected Aggregator factorize(ColumnSelectorFactory metricFactory, BaseFloatColumnValueSelector selector)
   {
-    return new FloatMaxBufferAggregator(getFloatColumnSelector(metricFactory, Float.NEGATIVE_INFINITY));
+    return new FloatMaxAggregator(selector);
   }
 
   @Override
-  public Object combine(Object lhs, Object rhs)
+  protected BufferAggregator factorizeBuffered(
+      ColumnSelectorFactory metricFactory,
+      BaseFloatColumnValueSelector selector
+  )
   {
+    return new FloatMaxBufferAggregator(selector);
+  }
+
+  @Override
+  @Nullable
+  public Object combine(@Nullable Object lhs, @Nullable Object rhs)
+  {
+    if (rhs == null) {
+      return lhs;
+    }
+    if (lhs == null) {
+      return rhs;
+    }
     return FloatMaxAggregator.combineValues(lhs, rhs);
   }
 

processing/src/main/java/io/druid/query/aggregation/FloatMinAggregatorFactory.java

@@ -24,8 +24,10 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import io.druid.java.util.common.StringUtils;
 import io.druid.math.expr.ExprMacroTable;
+import io.druid.segment.BaseFloatColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.List;
@@ -51,20 +53,39 @@ public class FloatMinAggregatorFactory extends SimpleFloatAggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected BaseFloatColumnValueSelector selector(ColumnSelectorFactory metricFactory)
   {
-    return new FloatMinAggregator(getFloatColumnSelector(metricFactory, Float.POSITIVE_INFINITY));
+    return getFloatColumnSelector(
+        metricFactory,
+        Float.POSITIVE_INFINITY
+    );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  protected Aggregator factorize(ColumnSelectorFactory metricFactory, BaseFloatColumnValueSelector selector)
   {
-    return new FloatMinBufferAggregator(getFloatColumnSelector(metricFactory, Float.POSITIVE_INFINITY));
+    return new FloatMinAggregator(selector);
   }
 
   @Override
-  public Object combine(Object lhs, Object rhs)
+  protected BufferAggregator factorizeBuffered(
+      ColumnSelectorFactory metricFactory,
+      BaseFloatColumnValueSelector selector
+  )
   {
+    return new FloatMinBufferAggregator(selector);
+  }
+
+  @Override
+  @Nullable
+  public Object combine(@Nullable Object lhs, @Nullable Object rhs)
+  {
+    if (rhs == null) {
+      return lhs;
+    }
+    if (lhs == null) {
+      return rhs;
+    }
     return FloatMinAggregator.combineValues(lhs, rhs);
   }
 

processing/src/main/java/io/druid/query/aggregation/FloatSumAggregatorFactory.java

@@ -24,8 +24,10 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import io.druid.java.util.common.StringUtils;
 import io.druid.math.expr.ExprMacroTable;
+import io.druid.segment.BaseFloatColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.List;
@@ -51,20 +53,39 @@ public class FloatSumAggregatorFactory extends SimpleFloatAggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected BaseFloatColumnValueSelector selector(ColumnSelectorFactory metricFactory)
   {
-    return new FloatSumAggregator(getFloatColumnSelector(metricFactory, 0.0f));
+    return getFloatColumnSelector(
+        metricFactory,
+        0.0f
+    );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  protected Aggregator factorize(ColumnSelectorFactory metricFactory, BaseFloatColumnValueSelector selector)
   {
-    return new FloatSumBufferAggregator(getFloatColumnSelector(metricFactory, 0.0f));
+    return new FloatSumAggregator(selector);
   }
 
   @Override
-  public Object combine(Object lhs, Object rhs)
+  protected BufferAggregator factorizeBuffered(
+      ColumnSelectorFactory metricFactory,
+      BaseFloatColumnValueSelector selector
+  )
   {
+    return new FloatSumBufferAggregator(selector);
+  }
+
+  @Override
+  @Nullable
+  public Object combine(@Nullable Object lhs, @Nullable Object rhs)
+  {
+    if (rhs == null) {
+      return lhs;
+    }
+    if (lhs == null) {
+      return rhs;
+    }
     return FloatSumAggregator.combineValues(lhs, rhs);
   }
 

processing/src/main/java/io/druid/query/aggregation/LongMaxAggregatorFactory.java

@@ -24,8 +24,10 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import io.druid.java.util.common.StringUtils;
 import io.druid.math.expr.ExprMacroTable;
+import io.druid.segment.BaseLongColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.List;
@@ -51,20 +53,39 @@ public class LongMaxAggregatorFactory extends SimpleLongAggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected BaseLongColumnValueSelector selector(ColumnSelectorFactory metricFactory)
   {
-    return new LongMaxAggregator(getLongColumnSelector(metricFactory, Long.MIN_VALUE));
+    return getLongColumnSelector(
+        metricFactory,
+        Long.MIN_VALUE
+    );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  protected Aggregator factorize(ColumnSelectorFactory metricFactory, BaseLongColumnValueSelector selector)
   {
-    return new LongMaxBufferAggregator(getLongColumnSelector(metricFactory, Long.MIN_VALUE));
+    return new LongMaxAggregator(selector);
   }
 
   @Override
-  public Object combine(Object lhs, Object rhs)
+  protected BufferAggregator factorizeBuffered(
+      ColumnSelectorFactory metricFactory,
+      BaseLongColumnValueSelector selector
+  )
   {
+    return new LongMaxBufferAggregator(selector);
+  }
+
+  @Override
+  @Nullable
+  public Object combine(@Nullable Object lhs, @Nullable Object rhs)
+  {
+    if (rhs == null) {
+      return lhs;
+    }
+    if (lhs == null) {
+      return rhs;
+    }
     return LongMaxAggregator.combineValues(lhs, rhs);
   }
 

processing/src/main/java/io/druid/query/aggregation/LongMinAggregatorFactory.java

@@ -24,8 +24,10 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import io.druid.java.util.common.StringUtils;
 import io.druid.math.expr.ExprMacroTable;
+import io.druid.segment.BaseLongColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.List;
@@ -51,20 +53,36 @@ public class LongMinAggregatorFactory extends SimpleLongAggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected BaseLongColumnValueSelector selector(ColumnSelectorFactory metricFactory)
   {
-    return new LongMinAggregator(getLongColumnSelector(metricFactory, Long.MAX_VALUE));
+    return getLongColumnSelector(
+        metricFactory,
+        Long.MAX_VALUE
+    );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  public Aggregator factorize(ColumnSelectorFactory metricFactory, BaseLongColumnValueSelector selector)
   {
-    return new LongMinBufferAggregator(getLongColumnSelector(metricFactory, Long.MAX_VALUE));
+    return new LongMinAggregator(selector);
   }
 
   @Override
-  public Object combine(Object lhs, Object rhs)
+  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, BaseLongColumnValueSelector selector)
   {
+    return new LongMinBufferAggregator(selector);
+  }
+
+  @Override
+  @Nullable
+  public Object combine(@Nullable Object lhs, @Nullable Object rhs)
+  {
+    if (rhs == null) {
+      return lhs;
+    }
+    if (lhs == null) {
+      return rhs;
+    }
     return LongMinAggregator.combineValues(lhs, rhs);
   }
 

processing/src/main/java/io/druid/query/aggregation/LongSumAggregatorFactory.java

@@ -24,8 +24,10 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import io.druid.java.util.common.StringUtils;
 import io.druid.math.expr.ExprMacroTable;
+import io.druid.segment.BaseLongColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Collections;
 import java.util.List;
@@ -51,20 +53,39 @@ public class LongSumAggregatorFactory extends SimpleLongAggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected BaseLongColumnValueSelector selector(ColumnSelectorFactory metricFactory)
   {
-    return new LongSumAggregator(getLongColumnSelector(metricFactory, 0L));
+    return getLongColumnSelector(
+        metricFactory,
+        0L
+    );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  protected Aggregator factorize(ColumnSelectorFactory metricFactory, BaseLongColumnValueSelector selector)
   {
-    return new LongSumBufferAggregator(getLongColumnSelector(metricFactory, 0L));
+    return new LongSumAggregator(selector);
   }
 
   @Override
-  public Object combine(Object lhs, Object rhs)
+  protected BufferAggregator factorizeBuffered(
+      ColumnSelectorFactory metricFactory,
+      BaseLongColumnValueSelector selector
+  )
   {
+    return new LongSumBufferAggregator(selector);
+  }
+
+  @Override
+  @Nullable
+  public Object combine(@Nullable Object lhs, @Nullable Object rhs)
+  {
+    if (rhs == null) {
+      return lhs;
+    }
+    if (lhs == null) {
+      return rhs;
+    }
     return LongSumAggregator.combineValues(lhs, rhs);
   }
 

processing/src/main/java/io/druid/query/aggregation/NullableAggregateCombiner.java

@@ -0,0 +1,117 @@
+/*
+ * 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 io.druid.query.aggregation;
+
+import io.druid.guice.annotations.PublicApi;
+import io.druid.segment.BaseNullableColumnValueSelector;
+import io.druid.segment.ColumnValueSelector;
+
+import javax.annotation.Nullable;
+
+/**
+ * The result of a NullableAggregateCombiner will be null if all the values to be combined are null values or no values
+ * are combined at all. If any of the value is non-null, the result would be the value of the delegate combiner.
+ * Note that the delegate combiner is not required to perform check for {@link BaseNullableColumnValueSelector#isNull()}
+ * on the selector as only non-null values will be passed to the delegate combiner.
+ * This class is only used when SQL compatible null handling is enabled.
+ */
+@PublicApi
+public final class NullableAggregateCombiner<T> implements AggregateCombiner<T>
+{
+  private boolean isNullResult = true;
+
+  private final AggregateCombiner<T> delegate;
+
+  public NullableAggregateCombiner(AggregateCombiner<T> delegate)
+  {
+    this.delegate = delegate;
+  }
+
+  @Override
+  public void reset(ColumnValueSelector selector)
+  {
+    if (selector.isNull()) {
+      isNullResult = true;
+    } else {
+      isNullResult = false;
+      delegate.reset(selector);
+    }
+  }
+
+  @Override
+  public void fold(ColumnValueSelector selector)
+  {
+    boolean isNotNull = !selector.isNull();
+    if (isNotNull) {
+      if (isNullResult) {
+        isNullResult = false;
+        delegate.reset(selector);
+      } else {
+        delegate.fold(selector);
+      }
+    }
+  }
+
+  @Override
+  public float getFloat()
+  {
+    if (isNullResult) {
+      throw new IllegalStateException("Cannot return primitive float for Null Value");
+    }
+    return delegate.getFloat();
+  }
+
+  @Override
+  public double getDouble()
+  {
+    if (isNullResult) {
+      throw new IllegalStateException("Cannot return double for Null Value");
+    }
+    return delegate.getDouble();
+  }
+
+  @Override
+  public long getLong()
+  {
+    if (isNullResult) {
+      throw new IllegalStateException("Cannot return long for Null Value");
+    }
+    return delegate.getLong();
+  }
+
+  @Override
+  public boolean isNull()
+  {
+    return isNullResult || delegate.isNull();
+  }
+
+  @Nullable
+  @Override
+  public T getObject()
+  {
+    return isNullResult ? null : delegate.getObject();
+  }
+
+  @Override
+  public Class classOfObject()
+  {
+    return delegate.classOfObject();
+  }
+}

processing/src/main/java/io/druid/query/aggregation/NullableAggregator.java

@@ -0,0 +1,107 @@
+/*
+ * 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 io.druid.query.aggregation;
+
+import io.druid.guice.annotations.PublicApi;
+import io.druid.segment.BaseNullableColumnValueSelector;
+
+import javax.annotation.Nullable;
+
+/**
+ * The result of a NullableAggregator will be null if all the values to be aggregated are null values
+ * or no values are aggregated at all. If any of the value is non-null, the result would be the aggregated
+ * value of the delegate aggregator. Note that the delegate aggregator is not required to perform check for
+ * {@link BaseNullableColumnValueSelector#isNull()} on the selector as only non-null values will be passed
+ * to the delegate aggregator. This class is only used when SQL compatible null handling is enabled.
+ */
+@PublicApi
+public final class NullableAggregator implements Aggregator
+{
+  private final Aggregator delegate;
+  private final BaseNullableColumnValueSelector selector;
+  private boolean isNullResult = true;
+
+  public NullableAggregator(Aggregator delegate, BaseNullableColumnValueSelector selector)
+  {
+    this.delegate = delegate;
+    this.selector = selector;
+  }
+
+  @Override
+  public void aggregate()
+  {
+    boolean isNotNull = !selector.isNull();
+    if (isNotNull) {
+      if (isNullResult) {
+        isNullResult = false;
+      }
+      delegate.aggregate();
+    }
+  }
+
+  @Override
+  @Nullable
+  public Object get()
+  {
+    if (isNullResult) {
+      return null;
+    }
+    return delegate.get();
+  }
+
+  @Override
+  public float getFloat()
+  {
+    if (isNullResult) {
+      throw new IllegalStateException("Cannot return float for Null Value");
+    }
+    return delegate.getFloat();
+  }
+
+  @Override
+  public long getLong()
+  {
+    if (isNullResult) {
+      throw new IllegalStateException("Cannot return long for Null Value");
+    }
+    return delegate.getLong();
+  }
+
+  @Override
+  public double getDouble()
+  {
+    if (isNullResult) {
+      throw new IllegalStateException("Cannot return double for Null Value");
+    }
+    return delegate.getDouble();
+  }
+
+  @Override
+  public boolean isNull()
+  {
+    return isNullResult || delegate.isNull();
+  }
+
+  @Override
+  public void close()
+  {
+    delegate.close();
+  }
+}

processing/src/main/java/io/druid/query/aggregation/NullableAggregatorFactory.java

@@ -0,0 +1,95 @@
+/*
+ * 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 io.druid.query.aggregation;
+
+
+import io.druid.common.config.NullHandling;
+import io.druid.guice.annotations.ExtensionPoint;
+import io.druid.segment.BaseNullableColumnValueSelector;
+import io.druid.segment.ColumnSelectorFactory;
+import io.druid.segment.ColumnValueSelector;
+
+/**
+ * Abstract class with functionality to wrap {@link Aggregator}, {@link BufferAggregator} and {@link AggregateCombiner}
+ * to support nullable aggregations for SQL compatibility. Implementations of {@link AggregatorFactory} which need to
+ * Support Nullable Aggregations are encouraged to extend this class.
+ */
+@ExtensionPoint
+public abstract class NullableAggregatorFactory<T extends BaseNullableColumnValueSelector> extends AggregatorFactory
+{
+  @Override
+  public final Aggregator factorize(ColumnSelectorFactory metricFactory)
+  {
+    T selector = selector(metricFactory);
+    Aggregator aggregator = factorize(metricFactory, selector);
+    return NullHandling.replaceWithDefault() ? aggregator : new NullableAggregator(aggregator, selector);
+  }
+
+  @Override
+  public final BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  {
+    T selector = selector(metricFactory);
+    BufferAggregator aggregator = factorizeBuffered(metricFactory, selector);
+    return NullHandling.replaceWithDefault() ? aggregator : new NullableBufferAggregator(aggregator, selector);
+  }
+
+  @Override
+  public final AggregateCombiner makeNullableAggregateCombiner()
+  {
+    AggregateCombiner combiner = makeAggregateCombiner();
+    return NullHandling.replaceWithDefault() ? combiner : new NullableAggregateCombiner(combiner);
+  }
+
+  @Override
+  public final int getMaxIntermediateSizeWithNulls()
+  {
+    return getMaxIntermediateSize() + (NullHandling.replaceWithDefault() ? 0 : Byte.BYTES);
+  }
+
+  // ---- ABSTRACT METHODS BELOW ------
+
+  /**
+   * Creates a {@link ColumnValueSelector} for the aggregated column.
+   *
+   * @see ColumnValueSelector
+   */
+  protected abstract T selector(ColumnSelectorFactory metricFactory);
+
+  /**
+   * Creates an {@link Aggregator} to aggregate values from several rows, by using the provided selector.
+   * @param metricFactory metricFactory
+   * @param selector {@link ColumnValueSelector} for the column to aggregate.
+   *
+   * @see Aggregator
+   */
+  protected abstract Aggregator factorize(ColumnSelectorFactory metricFactory, T selector);
+
+  /**
+   * Creates an {@link BufferAggregator} to aggregate values from several rows into a ByteBuffer.
+   * @param metricFactory metricFactory
+   * @param selector {@link ColumnValueSelector} for the column to aggregate.
+   *
+   * @see BufferAggregator
+   */
+  protected abstract BufferAggregator factorizeBuffered(
+      ColumnSelectorFactory metricFactory,
+      T selector
+  );
+}

processing/src/main/java/io/druid/query/aggregation/NullableBufferAggregator.java

@@ -0,0 +1,119 @@
+/*
+ * 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 io.druid.query.aggregation;
+
+import io.druid.common.config.NullHandling;
+import io.druid.guice.annotations.PublicApi;
+import io.druid.segment.BaseNullableColumnValueSelector;
+
+import javax.annotation.Nullable;
+import java.nio.ByteBuffer;
+
+/**
+ * The result of a NullableBufferAggregator will be null if all the values to be aggregated are null values or no values
+ * are aggregated at all. If any of the value is non-null, the result would be the aggregated value of the delegate
+ * aggregator. Note that the delegate aggregator is not required to perform check for
+ * {@link BaseNullableColumnValueSelector#isNull()} on the selector as only non-null values will be passed to the
+ * delegate aggregator. This class is only used when SQL compatible null handling is enabled.
+ * When writing aggregated result to buffer, it will write an additional byte to store the nullability of the
+ * aggregated result.
+ * Buffer Layout - 1 byte for storing nullability + delegate storage bytes.
+ */
+@PublicApi
+public final class NullableBufferAggregator implements BufferAggregator
+{
+
+  private final BufferAggregator delegate;
+  private final BaseNullableColumnValueSelector selector;
+
+  public NullableBufferAggregator(BufferAggregator delegate, BaseNullableColumnValueSelector selector)
+  {
+    this.delegate = delegate;
+    this.selector = selector;
+  }
+
+  @Override
+  public void init(ByteBuffer buf, int position)
+  {
+    buf.put(position, NullHandling.IS_NULL_BYTE);
+    delegate.init(buf, position + Byte.BYTES);
+  }
+
+  @Override
+  public void aggregate(ByteBuffer buf, int position)
+  {
+    boolean isNotNull = !selector.isNull();
+    if (isNotNull) {
+      if (buf.get(position) == NullHandling.IS_NULL_BYTE) {
+        buf.put(position, NullHandling.IS_NOT_NULL_BYTE);
+      }
+      delegate.aggregate(buf, position + Byte.BYTES);
+    }
+  }
+
+  @Override
+  @Nullable
+  public Object get(ByteBuffer buf, int position)
+  {
+    if (buf.get(position) == NullHandling.IS_NULL_BYTE) {
+      return null;
+    }
+    return delegate.get(buf, position + Byte.BYTES);
+  }
+
+  @Override
+  public float getFloat(ByteBuffer buf, int position)
+  {
+    if (buf.get(position) == NullHandling.IS_NULL_BYTE) {
+      throw new IllegalStateException("Cannot return float for Null Value");
+    }
+    return delegate.getFloat(buf, position + Byte.BYTES);
+  }
+
+  @Override
+  public long getLong(ByteBuffer buf, int position)
+  {
+    if (buf.get(position) == NullHandling.IS_NULL_BYTE) {
+      throw new IllegalStateException("Cannot return long for Null Value");
+    }
+    return delegate.getLong(buf, position + Byte.BYTES);
+  }
+
+  @Override
+  public double getDouble(ByteBuffer buf, int position)
+  {
+    if (buf.get(position) == NullHandling.IS_NULL_BYTE) {
+      throw new IllegalStateException("Cannot return double for Null Value");
+    }
+    return delegate.getDouble(buf, position + Byte.BYTES);
+  }
+
+  @Override
+  public boolean isNull(ByteBuffer buf, int position)
+  {
+    return buf.get(position) == NullHandling.IS_NULL_BYTE || delegate.isNull(buf, position + Byte.BYTES);
+  }
+
+  @Override
+  public void close()
+  {
+    delegate.close();
+  }
+}

processing/src/main/java/io/druid/query/aggregation/PostAggregator.java

@@ -22,6 +22,7 @@ package io.druid.query.aggregation;
 import io.druid.guice.annotations.ExtensionPoint;
 import io.druid.java.util.common.Cacheable;
 
+import javax.annotation.Nullable;
 import java.util.Comparator;
 import java.util.Map;
 import java.util.Set;
@@ -36,6 +37,7 @@ public interface PostAggregator extends Cacheable
 
   Comparator getComparator();
 
+  @Nullable
   Object compute(Map<String, Object> combinedAggregators);
 
   String getName();

processing/src/main/java/io/druid/query/aggregation/SimpleDoubleAggregatorFactory.java

@@ -28,12 +28,13 @@ import io.druid.segment.BaseDoubleColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
 import io.druid.segment.column.Column;
 
+import javax.annotation.Nullable;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 
-public abstract class SimpleDoubleAggregatorFactory extends AggregatorFactory
+public abstract class SimpleDoubleAggregatorFactory extends NullableAggregatorFactory<BaseDoubleColumnValueSelector>
 {
   protected final String name;
   protected final String fieldName;
@@ -103,7 +104,8 @@ public abstract class SimpleDoubleAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Object finalizeComputation(Object object)
+  @Nullable
+  public Object finalizeComputation(@Nullable Object object)
   {
     return object;
   }

processing/src/main/java/io/druid/query/aggregation/SimpleFloatAggregatorFactory.java

@@ -27,12 +27,13 @@ import io.druid.math.expr.Parser;
 import io.druid.segment.BaseFloatColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
 
+import javax.annotation.Nullable;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 
-public abstract class SimpleFloatAggregatorFactory extends AggregatorFactory
+public abstract class SimpleFloatAggregatorFactory extends NullableAggregatorFactory<BaseFloatColumnValueSelector>
 {
   protected final String name;
   protected final String fieldName;
@@ -97,7 +98,8 @@ public abstract class SimpleFloatAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Object finalizeComputation(Object object)
+  @Nullable
+  public Object finalizeComputation(@Nullable Object object)
   {
     return object;
   }

processing/src/main/java/io/druid/query/aggregation/SimpleLongAggregatorFactory.java

@@ -27,12 +27,13 @@ import io.druid.math.expr.Parser;
 import io.druid.segment.BaseLongColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
 
+import javax.annotation.Nullable;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
 
-public abstract class SimpleLongAggregatorFactory extends AggregatorFactory
+public abstract class SimpleLongAggregatorFactory extends NullableAggregatorFactory<BaseLongColumnValueSelector>
 {
   protected final String name;
   protected final String fieldName;
@@ -93,7 +94,8 @@ public abstract class SimpleLongAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Object finalizeComputation(Object object)
+  @Nullable
+  public Object finalizeComputation(@Nullable Object object)
   {
     return object;
   }

processing/src/main/java/io/druid/query/aggregation/cardinality/types/DoubleCardinalityAggregatorColumnSelectorStrategy.java

@@ -20,23 +20,33 @@
 package io.druid.query.aggregation.cardinality.types;
 
 import com.google.common.hash.Hasher;
+import io.druid.common.config.NullHandling;
 import io.druid.hll.HyperLogLogCollector;
 import io.druid.query.aggregation.cardinality.CardinalityAggregator;
 import io.druid.segment.BaseDoubleColumnValueSelector;
 
-
+/**
+ * If performance of this class appears to be a bottleneck for somebody,
+ * one simple way to improve it is to split it into two different classes,
+ * one that is used when {@link NullHandling#replaceWithDefault()} is false,
+ * and one - when it's true, moving this computation out of the tight loop
+ */
 public class DoubleCardinalityAggregatorColumnSelectorStrategy
     implements CardinalityAggregatorColumnSelectorStrategy<BaseDoubleColumnValueSelector>
 {
   @Override
-  public void hashRow(BaseDoubleColumnValueSelector dimSelector, Hasher hasher)
+  public void hashRow(BaseDoubleColumnValueSelector selector, Hasher hasher)
   {
-    hasher.putDouble(dimSelector.getDouble());
+    if (NullHandling.replaceWithDefault() || !selector.isNull()) {
+      hasher.putDouble(selector.getDouble());
+    }
   }
 
   @Override
-  public void hashValues(BaseDoubleColumnValueSelector dimSelector, HyperLogLogCollector collector)
+  public void hashValues(BaseDoubleColumnValueSelector selector, HyperLogLogCollector collector)
   {
-    collector.add(CardinalityAggregator.hashFn.hashLong(Double.doubleToLongBits(dimSelector.getDouble())).asBytes());
+    if (NullHandling.replaceWithDefault() || !selector.isNull()) {
+      collector.add(CardinalityAggregator.hashFn.hashLong(Double.doubleToLongBits(selector.getDouble())).asBytes());
+    }
   }
 }

processing/src/main/java/io/druid/query/aggregation/cardinality/types/FloatCardinalityAggregatorColumnSelectorStrategy.java

@@ -20,22 +20,33 @@
 package io.druid.query.aggregation.cardinality.types;
 
 import com.google.common.hash.Hasher;
+import io.druid.common.config.NullHandling;
 import io.druid.hll.HyperLogLogCollector;
 import io.druid.query.aggregation.cardinality.CardinalityAggregator;
 import io.druid.segment.BaseFloatColumnValueSelector;
 
+/**
+ * If performance of this class appears to be a bottleneck for somebody,
+ * one simple way to improve it is to split it into two different classes,
+ * one that is used when {@link NullHandling#replaceWithDefault()} is false,
+ * and one - when it's true, moving this computation out of the tight loop
+ */
 public class FloatCardinalityAggregatorColumnSelectorStrategy
     implements CardinalityAggregatorColumnSelectorStrategy<BaseFloatColumnValueSelector>
 {
   @Override
   public void hashRow(BaseFloatColumnValueSelector selector, Hasher hasher)
   {
+    if (NullHandling.replaceWithDefault() || !selector.isNull()) {
       hasher.putFloat(selector.getFloat());
     }
+  }
 
   @Override
   public void hashValues(BaseFloatColumnValueSelector selector, HyperLogLogCollector collector)
   {
+    if (NullHandling.replaceWithDefault() || !selector.isNull()) {
       collector.add(CardinalityAggregator.hashFn.hashInt(Float.floatToIntBits(selector.getFloat())).asBytes());
     }
+  }
 }

processing/src/main/java/io/druid/query/aggregation/cardinality/types/LongCardinalityAggregatorColumnSelectorStrategy.java

@@ -20,22 +20,33 @@
 package io.druid.query.aggregation.cardinality.types;
 
 import com.google.common.hash.Hasher;
+import io.druid.common.config.NullHandling;
 import io.druid.hll.HyperLogLogCollector;
 import io.druid.query.aggregation.cardinality.CardinalityAggregator;
 import io.druid.segment.BaseLongColumnValueSelector;
 
+/**
+ * If performance of this class appears to be a bottleneck for somebody,
+ * one simple way to improve it is to split it into two different classes,
+ * one that is used when {@link NullHandling#replaceWithDefault()} is false,
+ * and one - when it's true, moving this computation out of the tight loop
+ */
 public class LongCardinalityAggregatorColumnSelectorStrategy
     implements CardinalityAggregatorColumnSelectorStrategy<BaseLongColumnValueSelector>
 {
   @Override
-  public void hashRow(BaseLongColumnValueSelector dimSelector, Hasher hasher)
+  public void hashRow(BaseLongColumnValueSelector selector, Hasher hasher)
   {
-    hasher.putLong(dimSelector.getLong());
+    if (NullHandling.replaceWithDefault() || !selector.isNull()) {
+      hasher.putLong(selector.getLong());
+    }
   }
 
   @Override
-  public void hashValues(BaseLongColumnValueSelector dimSelector, HyperLogLogCollector collector)
+  public void hashValues(BaseLongColumnValueSelector selector, HyperLogLogCollector collector)
   {
-    collector.add(CardinalityAggregator.hashFn.hashLong(dimSelector.getLong()).asBytes());
+    if (NullHandling.replaceWithDefault() || !selector.isNull()) {
+      collector.add(CardinalityAggregator.hashFn.hashLong(selector.getLong()).asBytes());
+    }
   }
 }

processing/src/main/java/io/druid/query/aggregation/cardinality/types/StringCardinalityAggregatorColumnSelectorStrategy.java

@@ -20,6 +20,7 @@
 package io.druid.query.aggregation.cardinality.types;
 
 import com.google.common.hash.Hasher;
+import io.druid.common.config.NullHandling;
 import io.druid.hll.HyperLogLogCollector;
 import io.druid.query.aggregation.cardinality.CardinalityAggregator;
 import io.druid.segment.DimensionSelector;
@@ -40,13 +41,26 @@ public class StringCardinalityAggregatorColumnSelectorStrategy implements Cardin
     // nothing to add to hasher if size == 0, only handle size == 1 and size != 0 cases.
     if (size == 1) {
       final String value = dimSelector.lookupName(row.get(0));
+      if (NullHandling.replaceWithDefault() || value != null) {
         hasher.putUnencodedChars(nullToSpecial(value));
+      }
     } else if (size != 0) {
+      boolean hasNonNullValue = false;
       final String[] values = new String[size];
       for (int i = 0; i < size; ++i) {
         final String value = dimSelector.lookupName(row.get(i));
+        // SQL standard spec does not count null values,
+        // Skip counting null values when we are not replacing null with default value.
+        // A special value for null in case null handling is configured to use empty string for null.
+        if (NullHandling.sqlCompatible() && !hasNonNullValue && value != null) {
+          hasNonNullValue = true;
+        }
         values[i] = nullToSpecial(value);
       }
+      // SQL standard spec does not count null values,
+      // Skip counting null values when we are not replacing null with default value.
+      // A special value for null in case null handling is configured to use empty string for null.
+      if (NullHandling.replaceWithDefault() || hasNonNullValue) {
         // Values need to be sorted to ensure consistent multi-value ordering across different segments
         Arrays.sort(values);
         for (int i = 0; i < size; ++i) {
@@ -57,6 +71,7 @@ public class StringCardinalityAggregatorColumnSelectorStrategy implements Cardin
         }
       }
     }
+  }
 
   @Override
   public void hashValues(DimensionSelector dimSelector, HyperLogLogCollector collector)
@@ -65,9 +80,14 @@ public class StringCardinalityAggregatorColumnSelectorStrategy implements Cardin
     for (int i = 0, rowSize = row.size(); i < rowSize; i++) {
       int index = row.get(i);
       final String value = dimSelector.lookupName(index);
+      // SQL standard spec does not count null values,
+      // Skip counting null values when we are not replacing null with default value.
+      // A special value for null in case null handling is configured to use empty string for null.
+      if (NullHandling.replaceWithDefault() || value != null) {
         collector.add(CardinalityAggregator.hashFn.hashUnencodedChars(nullToSpecial(value)).asBytes());
       }
     }
+  }
 
   private String nullToSpecial(String value)
   {

processing/src/main/java/io/druid/query/aggregation/first/DoubleFirstAggregatorFactory.java

@@ -32,11 +32,13 @@ import io.druid.query.aggregation.Aggregator;
 import io.druid.query.aggregation.AggregatorFactory;
 import io.druid.query.aggregation.AggregatorUtil;
 import io.druid.query.aggregation.BufferAggregator;
+import io.druid.query.aggregation.NullableAggregatorFactory;
 import io.druid.query.monomorphicprocessing.RuntimeShapeInspector;
-import io.druid.segment.BaseObjectColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
+import io.druid.segment.ColumnValueSelector;
 import io.druid.segment.column.Column;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Arrays;
 import java.util.Collections;
@@ -45,7 +47,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 
-public class DoubleFirstAggregatorFactory extends AggregatorFactory
+public class DoubleFirstAggregatorFactory extends NullableAggregatorFactory<ColumnValueSelector>
 {
   public static final Comparator VALUE_COMPARATOR = (o1, o2) -> Doubles.compare(
       ((SerializablePair<Long, Double>) o1).rhs,
@@ -76,20 +78,26 @@ public class DoubleFirstAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected ColumnValueSelector selector(ColumnSelectorFactory metricFactory)
+  {
+    return metricFactory.makeColumnValueSelector(fieldName);
+  }
+
+  @Override
+  protected Aggregator factorize(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
   {
     return new DoubleFirstAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName)
+        selector
     );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  protected BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
   {
     return new DoubleFirstBufferAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName)
+        selector
     );
   }
 
@@ -100,8 +108,15 @@ public class DoubleFirstAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Object combine(Object lhs, Object rhs)
+  @Nullable
+  public Object combine(@Nullable Object lhs, @Nullable Object rhs)
   {
+    if (rhs == null) {
+      return lhs;
+    }
+    if (lhs == null) {
+      return rhs;
+    }
     return TIME_COMPARATOR.compare(lhs, rhs) <= 0 ? lhs : rhs;
   }
 
@@ -117,9 +132,8 @@ public class DoubleFirstAggregatorFactory extends AggregatorFactory
     return new DoubleFirstAggregatorFactory(name, name)
     {
       @Override
-      public Aggregator factorize(ColumnSelectorFactory metricFactory)
+      public Aggregator factorize(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
       {
-        final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(name);
         return new DoubleFirstAggregator(null, null)
         {
           @Override
@@ -135,9 +149,8 @@ public class DoubleFirstAggregatorFactory extends AggregatorFactory
       }
 
       @Override
-      public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+      public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
       {
-        final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(name);
         return new DoubleFirstBufferAggregator(null, null)
         {
           @Override
@@ -175,9 +188,10 @@ public class DoubleFirstAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Object finalizeComputation(Object object)
+  @Nullable
+  public Object finalizeComputation(@Nullable Object object)
   {
-    return ((SerializablePair<Long, Double>) object).rhs;
+    return object == null ? null : ((SerializablePair<Long, Double>) object).rhs;
   }
 
   @Override

processing/src/main/java/io/druid/query/aggregation/first/FloatFirstAggregatorFactory.java

@@ -32,11 +32,13 @@ import io.druid.query.aggregation.Aggregator;
 import io.druid.query.aggregation.AggregatorFactory;
 import io.druid.query.aggregation.AggregatorUtil;
 import io.druid.query.aggregation.BufferAggregator;
+import io.druid.query.aggregation.NullableAggregatorFactory;
 import io.druid.query.monomorphicprocessing.RuntimeShapeInspector;
-import io.druid.segment.BaseObjectColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
+import io.druid.segment.ColumnValueSelector;
 import io.druid.segment.column.Column;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Arrays;
 import java.util.Collections;
@@ -45,7 +47,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 
-public class FloatFirstAggregatorFactory extends AggregatorFactory
+public class FloatFirstAggregatorFactory extends NullableAggregatorFactory<ColumnValueSelector>
 {
   public static final Comparator VALUE_COMPARATOR = (o1, o2) -> Doubles.compare(
       ((SerializablePair<Long, Float>) o1).rhs,
@@ -74,20 +76,26 @@ public class FloatFirstAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected ColumnValueSelector selector(ColumnSelectorFactory metricFactory)
+  {
+    return metricFactory.makeColumnValueSelector(fieldName);
+  }
+
+  @Override
+  protected Aggregator factorize(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
   {
     return new FloatFirstAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName)
+        selector
     );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  protected BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
   {
     return new FloatFirstBufferAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName)
+        selector
     );
   }
 
@@ -98,8 +106,15 @@ public class FloatFirstAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Object combine(Object lhs, Object rhs)
+  @Nullable
+  public Object combine(@Nullable Object lhs, @Nullable Object rhs)
   {
+    if (rhs == null) {
+      return lhs;
+    }
+    if (lhs == null) {
+      return rhs;
+    }
     return TIME_COMPARATOR.compare(lhs, rhs) <= 0 ? lhs : rhs;
   }
 
@@ -115,9 +130,8 @@ public class FloatFirstAggregatorFactory extends AggregatorFactory
     return new FloatFirstAggregatorFactory(name, name)
     {
       @Override
-      public Aggregator factorize(ColumnSelectorFactory metricFactory)
+      public Aggregator factorize(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
       {
-        final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(name);
         return new FloatFirstAggregator(null, null)
         {
           @Override
@@ -133,9 +147,8 @@ public class FloatFirstAggregatorFactory extends AggregatorFactory
       }
 
       @Override
-      public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+      public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
       {
-        final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(name);
         return new FloatFirstBufferAggregator(null, null)
         {
           @Override
@@ -173,9 +186,10 @@ public class FloatFirstAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Object finalizeComputation(Object object)
+  @Nullable
+  public Object finalizeComputation(@Nullable Object object)
   {
-    return ((SerializablePair<Long, Float>) object).rhs;
+    return object == null ? null : ((SerializablePair<Long, Float>) object).rhs;
   }
 
   @Override

processing/src/main/java/io/druid/query/aggregation/first/LongFirstAggregatorFactory.java

@@ -31,11 +31,13 @@ import io.druid.query.aggregation.Aggregator;
 import io.druid.query.aggregation.AggregatorFactory;
 import io.druid.query.aggregation.AggregatorUtil;
 import io.druid.query.aggregation.BufferAggregator;
+import io.druid.query.aggregation.NullableAggregatorFactory;
 import io.druid.query.monomorphicprocessing.RuntimeShapeInspector;
-import io.druid.segment.BaseObjectColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
+import io.druid.segment.ColumnValueSelector;
 import io.druid.segment.column.Column;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Arrays;
 import java.util.Collections;
@@ -43,7 +45,7 @@ import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
 
-public class LongFirstAggregatorFactory extends AggregatorFactory
+public class LongFirstAggregatorFactory extends NullableAggregatorFactory<ColumnValueSelector>
 {
   public static final Comparator VALUE_COMPARATOR = (o1, o2) -> Longs.compare(
       ((SerializablePair<Long, Long>) o1).rhs,
@@ -67,20 +69,26 @@ public class LongFirstAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected ColumnValueSelector selector(ColumnSelectorFactory metricFactory)
+  {
+    return metricFactory.makeColumnValueSelector(fieldName);
+  }
+
+  @Override
+  protected Aggregator factorize(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
   {
     return new LongFirstAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName)
+        selector
     );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  protected BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
   {
     return new LongFirstBufferAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName)
+        selector
     );
   }
 
@@ -91,8 +99,15 @@ public class LongFirstAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Object combine(Object lhs, Object rhs)
+  @Nullable
+  public Object combine(@Nullable Object lhs, @Nullable Object rhs)
   {
+    if (lhs == null) {
+      return rhs;
+    }
+    if (rhs == null) {
+      return lhs;
+    }
     return DoubleFirstAggregatorFactory.TIME_COMPARATOR.compare(lhs, rhs) <= 0 ? lhs : rhs;
   }
 
@@ -108,9 +123,8 @@ public class LongFirstAggregatorFactory extends AggregatorFactory
     return new LongFirstAggregatorFactory(name, name)
     {
       @Override
-      public Aggregator factorize(ColumnSelectorFactory metricFactory)
+      public Aggregator factorize(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
       {
-        final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(name);
         return new LongFirstAggregator(null, null)
         {
           @Override
@@ -126,9 +140,8 @@ public class LongFirstAggregatorFactory extends AggregatorFactory
       }
 
       @Override
-      public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+      public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
       {
-        final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(name);
         return new LongFirstBufferAggregator(null, null)
         {
           @Override
@@ -166,9 +179,10 @@ public class LongFirstAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Object finalizeComputation(Object object)
+  @Nullable
+  public Object finalizeComputation(@Nullable Object object)
   {
-    return ((SerializablePair<Long, Long>) object).rhs;
+    return object == null ? null : ((SerializablePair<Long, Long>) object).rhs;
   }
 
   @Override

processing/src/main/java/io/druid/query/aggregation/first/StringFirstAggregatorFactory.java

@@ -29,8 +29,10 @@ import io.druid.query.aggregation.Aggregator;
 import io.druid.query.aggregation.AggregatorFactory;
 import io.druid.query.aggregation.AggregatorUtil;
 import io.druid.query.aggregation.BufferAggregator;
+import io.druid.query.aggregation.NullableAggregatorFactory;
 import io.druid.query.aggregation.SerializablePairLongString;
 import io.druid.query.cache.CacheKeyBuilder;
+import io.druid.segment.BaseObjectColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
 import io.druid.segment.column.Column;
 
@@ -42,7 +44,7 @@ import java.util.Map;
 import java.util.Objects;
 
 @JsonTypeName("stringFirst")
-public class StringFirstAggregatorFactory extends AggregatorFactory
+public class StringFirstAggregatorFactory extends NullableAggregatorFactory<BaseObjectColumnValueSelector>
 {
   public static final int DEFAULT_MAX_STRING_SIZE = 1024;
 
@@ -107,21 +109,27 @@ public class StringFirstAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected BaseObjectColumnValueSelector selector(ColumnSelectorFactory metricFactory)
+  {
+    return metricFactory.makeColumnValueSelector(fieldName);
+  }
+
+  @Override
+  public Aggregator factorize(ColumnSelectorFactory metricFactory, BaseObjectColumnValueSelector selector)
   {
     return new StringFirstAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName),
+        selector,
         maxStringBytes
     );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, BaseObjectColumnValueSelector selector)
   {
     return new StringFirstBufferAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName),
+        selector,
         maxStringBytes
     );
   }

processing/src/main/java/io/druid/query/aggregation/first/StringFirstFoldingAggregatorFactory.java

@@ -44,9 +44,8 @@ public class StringFirstFoldingAggregatorFactory extends StringFirstAggregatorFa
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  public Aggregator factorize(ColumnSelectorFactory metricFactory, BaseObjectColumnValueSelector selector)
   {
-    final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(getName());
     return new StringFirstAggregator(null, null, maxStringBytes)
     {
       @Override
@@ -62,9 +61,8 @@ public class StringFirstFoldingAggregatorFactory extends StringFirstAggregatorFa
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, BaseObjectColumnValueSelector selector)
   {
-    final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(getName());
     return new StringFirstBufferAggregator(null, null, maxStringBytes)
     {
       @Override

processing/src/main/java/io/druid/query/aggregation/last/DoubleLastAggregatorFactory.java

@@ -30,13 +30,15 @@ import io.druid.query.aggregation.Aggregator;
 import io.druid.query.aggregation.AggregatorFactory;
 import io.druid.query.aggregation.AggregatorUtil;
 import io.druid.query.aggregation.BufferAggregator;
+import io.druid.query.aggregation.NullableAggregatorFactory;
 import io.druid.query.aggregation.first.DoubleFirstAggregatorFactory;
 import io.druid.query.aggregation.first.LongFirstAggregatorFactory;
 import io.druid.query.monomorphicprocessing.RuntimeShapeInspector;
-import io.druid.segment.BaseObjectColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
+import io.druid.segment.ColumnValueSelector;
 import io.druid.segment.column.Column;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Arrays;
 import java.util.Collections;
@@ -45,7 +47,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 
-public class DoubleLastAggregatorFactory extends AggregatorFactory
+public class DoubleLastAggregatorFactory extends NullableAggregatorFactory<ColumnValueSelector>
 {
 
   private final String fieldName;
@@ -66,20 +68,26 @@ public class DoubleLastAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected ColumnValueSelector selector(ColumnSelectorFactory metricFactory)
+  {
+    return metricFactory.makeColumnValueSelector(fieldName);
+  }
+
+  @Override
+  protected Aggregator factorize(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
   {
     return new DoubleLastAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName)
+        selector
     );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  protected BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
   {
     return new DoubleLastBufferAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName)
+        selector
     );
   }
 
@@ -90,8 +98,15 @@ public class DoubleLastAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Object combine(Object lhs, Object rhs)
+  @Nullable
+  public Object combine(@Nullable Object lhs, @Nullable Object rhs)
   {
+    if (rhs == null) {
+      return lhs;
+    }
+    if (lhs == null) {
+      return rhs;
+    }
     return DoubleFirstAggregatorFactory.TIME_COMPARATOR.compare(lhs, rhs) > 0 ? lhs : rhs;
   }
 
@@ -107,9 +122,8 @@ public class DoubleLastAggregatorFactory extends AggregatorFactory
     return new DoubleLastAggregatorFactory(name, name)
     {
       @Override
-      public Aggregator factorize(ColumnSelectorFactory metricFactory)
+      public Aggregator factorize(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
       {
-        final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(name);
         return new DoubleLastAggregator(null, null)
         {
           @Override
@@ -125,9 +139,8 @@ public class DoubleLastAggregatorFactory extends AggregatorFactory
       }
 
       @Override
-      public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+      public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
       {
-        final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(name);
         return new DoubleLastBufferAggregator(null, null)
         {
           @Override
@@ -165,9 +178,10 @@ public class DoubleLastAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Object finalizeComputation(Object object)
+  @Nullable
+  public Object finalizeComputation(@Nullable Object object)
   {
-    return ((SerializablePair<Long, Double>) object).rhs;
+    return object == null ? null : ((SerializablePair<Long, Double>) object).rhs;
   }
 
   @Override

processing/src/main/java/io/druid/query/aggregation/last/FloatLastAggregatorFactory.java

@@ -30,13 +30,15 @@ import io.druid.query.aggregation.Aggregator;
 import io.druid.query.aggregation.AggregatorFactory;
 import io.druid.query.aggregation.AggregatorUtil;
 import io.druid.query.aggregation.BufferAggregator;
+import io.druid.query.aggregation.NullableAggregatorFactory;
 import io.druid.query.aggregation.first.FloatFirstAggregatorFactory;
 import io.druid.query.aggregation.first.LongFirstAggregatorFactory;
 import io.druid.query.monomorphicprocessing.RuntimeShapeInspector;
-import io.druid.segment.BaseObjectColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
+import io.druid.segment.ColumnValueSelector;
 import io.druid.segment.column.Column;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Arrays;
 import java.util.Collections;
@@ -45,7 +47,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 
-public class FloatLastAggregatorFactory extends AggregatorFactory
+public class FloatLastAggregatorFactory extends NullableAggregatorFactory<ColumnValueSelector>
 {
 
   private final String fieldName;
@@ -64,20 +66,26 @@ public class FloatLastAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected ColumnValueSelector selector(ColumnSelectorFactory metricFactory)
+  {
+    return metricFactory.makeColumnValueSelector(fieldName);
+  }
+
+  @Override
+  protected Aggregator factorize(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
   {
     return new FloatLastAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName)
+        selector
     );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  protected BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
   {
     return new FloatLastBufferAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName)
+        selector
     );
   }
 
@@ -88,8 +96,15 @@ public class FloatLastAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Object combine(Object lhs, Object rhs)
+  @Nullable
+  public Object combine(@Nullable Object lhs, @Nullable Object rhs)
   {
+    if (rhs == null) {
+      return lhs;
+    }
+    if (lhs == null) {
+      return rhs;
+    }
     return FloatFirstAggregatorFactory.TIME_COMPARATOR.compare(lhs, rhs) > 0 ? lhs : rhs;
   }
 
@@ -105,9 +120,8 @@ public class FloatLastAggregatorFactory extends AggregatorFactory
     return new FloatLastAggregatorFactory(name, name)
     {
       @Override
-      public Aggregator factorize(ColumnSelectorFactory metricFactory)
+      public Aggregator factorize(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
       {
-        final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(name);
         return new FloatLastAggregator(null, null)
         {
           @Override
@@ -123,9 +137,8 @@ public class FloatLastAggregatorFactory extends AggregatorFactory
       }
 
       @Override
-      public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+      public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
       {
-        final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(name);
         return new FloatLastBufferAggregator(null, null)
         {
           @Override
@@ -163,9 +176,10 @@ public class FloatLastAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Object finalizeComputation(Object object)
+  @Nullable
+  public Object finalizeComputation(@Nullable Object object)
   {
-    return ((SerializablePair<Long, Float>) object).rhs;
+    return object == null ? null : ((SerializablePair<Long, Float>) object).rhs;
   }
 
   @Override

processing/src/main/java/io/druid/query/aggregation/last/LongLastAggregatorFactory.java

@@ -30,13 +30,15 @@ import io.druid.query.aggregation.Aggregator;
 import io.druid.query.aggregation.AggregatorFactory;
 import io.druid.query.aggregation.AggregatorUtil;
 import io.druid.query.aggregation.BufferAggregator;
+import io.druid.query.aggregation.NullableAggregatorFactory;
 import io.druid.query.aggregation.first.DoubleFirstAggregatorFactory;
 import io.druid.query.aggregation.first.LongFirstAggregatorFactory;
 import io.druid.query.monomorphicprocessing.RuntimeShapeInspector;
-import io.druid.segment.BaseObjectColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
+import io.druid.segment.ColumnValueSelector;
 import io.druid.segment.column.Column;
 
+import javax.annotation.Nullable;
 import java.nio.ByteBuffer;
 import java.util.Arrays;
 import java.util.Collections;
@@ -45,7 +47,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 
-public class LongLastAggregatorFactory extends AggregatorFactory
+public class LongLastAggregatorFactory extends NullableAggregatorFactory<ColumnValueSelector>
 {
   private final String fieldName;
   private final String name;
@@ -63,20 +65,26 @@ public class LongLastAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected ColumnValueSelector selector(ColumnSelectorFactory metricFactory)
+  {
+    return metricFactory.makeColumnValueSelector(fieldName);
+  }
+
+  @Override
+  protected Aggregator factorize(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
   {
     return new LongLastAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName)
+        selector
     );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  protected BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
   {
     return new LongLastBufferAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName)
+        selector
     );
   }
 
@@ -87,8 +95,15 @@ public class LongLastAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Object combine(Object lhs, Object rhs)
+  @Nullable
+  public Object combine(@Nullable Object lhs, @Nullable Object rhs)
   {
+    if (rhs == null) {
+      return lhs;
+    }
+    if (lhs == null) {
+      return rhs;
+    }
     return DoubleFirstAggregatorFactory.TIME_COMPARATOR.compare(lhs, rhs) > 0 ? lhs : rhs;
   }
 
@@ -104,9 +119,8 @@ public class LongLastAggregatorFactory extends AggregatorFactory
     return new LongLastAggregatorFactory(name, name)
     {
       @Override
-      public Aggregator factorize(ColumnSelectorFactory metricFactory)
+      public Aggregator factorize(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
       {
-        final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(name);
         return new LongLastAggregator(null, null)
         {
           @Override
@@ -122,9 +136,8 @@ public class LongLastAggregatorFactory extends AggregatorFactory
       }
 
       @Override
-      public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+      public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, ColumnValueSelector selector)
       {
-        final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(name);
         return new LongLastBufferAggregator(null, null)
         {
           @Override
@@ -162,9 +175,10 @@ public class LongLastAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Object finalizeComputation(Object object)
+  @Nullable
+  public Object finalizeComputation(@Nullable Object object)
   {
-    return ((SerializablePair<Long, Long>) object).rhs;
+    return object == null ? null : ((SerializablePair<Long, Long>) object).rhs;
   }
 
   @Override

processing/src/main/java/io/druid/query/aggregation/last/StringLastAggregatorFactory.java

@@ -28,9 +28,11 @@ import io.druid.query.aggregation.Aggregator;
 import io.druid.query.aggregation.AggregatorFactory;
 import io.druid.query.aggregation.AggregatorUtil;
 import io.druid.query.aggregation.BufferAggregator;
+import io.druid.query.aggregation.NullableAggregatorFactory;
 import io.druid.query.aggregation.SerializablePairLongString;
 import io.druid.query.aggregation.first.StringFirstAggregatorFactory;
 import io.druid.query.cache.CacheKeyBuilder;
+import io.druid.segment.BaseObjectColumnValueSelector;
 import io.druid.segment.ColumnSelectorFactory;
 import io.druid.segment.column.Column;
 
@@ -43,7 +45,7 @@ import java.util.Objects;
 
 
 @JsonTypeName("stringLast")
-public class StringLastAggregatorFactory extends AggregatorFactory
+public class StringLastAggregatorFactory extends NullableAggregatorFactory<BaseObjectColumnValueSelector>
 {
   private final String fieldName;
   private final String name;
@@ -66,21 +68,27 @@ public class StringLastAggregatorFactory extends AggregatorFactory
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  protected BaseObjectColumnValueSelector selector(ColumnSelectorFactory metricFactory)
+  {
+    return metricFactory.makeColumnValueSelector(fieldName);
+  }
+
+  @Override
+  public Aggregator factorize(ColumnSelectorFactory metricFactory, BaseObjectColumnValueSelector selector)
   {
     return new StringLastAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName),
+        selector,
         maxStringBytes
     );
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, BaseObjectColumnValueSelector selector)
   {
     return new StringLastBufferAggregator(
         metricFactory.makeColumnValueSelector(Column.TIME_COLUMN_NAME),
-        metricFactory.makeColumnValueSelector(fieldName),
+        selector,
         maxStringBytes
     );
   }

processing/src/main/java/io/druid/query/aggregation/last/StringLastFoldingAggregatorFactory.java

@@ -44,9 +44,8 @@ public class StringLastFoldingAggregatorFactory extends StringLastAggregatorFact
   }
 
   @Override
-  public Aggregator factorize(ColumnSelectorFactory metricFactory)
+  public Aggregator factorize(ColumnSelectorFactory metricFactory, BaseObjectColumnValueSelector selector)
   {
-    final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(getName());
     return new StringLastAggregator(null, null, maxStringBytes)
     {
       @Override
@@ -62,9 +61,8 @@ public class StringLastFoldingAggregatorFactory extends StringLastAggregatorFact
   }
 
   @Override
-  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory)
+  public BufferAggregator factorizeBuffered(ColumnSelectorFactory metricFactory, BaseObjectColumnValueSelector selector)
   {
-    final BaseObjectColumnValueSelector selector = metricFactory.makeColumnValueSelector(getName());
     return new StringLastBufferAggregator(null, null, maxStringBytes)
     {
       @Override

processing/src/main/java/io/druid/query/aggregation/post/ArithmeticPostAggregator.java

@@ -24,6 +24,7 @@ import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.IAE;
 import io.druid.query.Queries;
 import io.druid.query.aggregation.AggregatorFactory;
@@ -109,11 +110,21 @@ public class ArithmeticPostAggregator implements PostAggregator
   public Object compute(Map<String, Object> values)
   {
     Iterator<PostAggregator> fieldsIter = fields.iterator();
-    double retVal = 0.0;
+    Double retVal = NullHandling.defaultDoubleValue();
     if (fieldsIter.hasNext()) {
-      retVal = ((Number) fieldsIter.next().compute(values)).doubleValue();
+      Number nextVal = (Number) fieldsIter.next().compute(values);
+      if (nextVal == null) {
+        // As per SQL standard if any of the value is null, arithmetic operators will return null.
+        return null;
+      }
+      retVal = nextVal.doubleValue();
       while (fieldsIter.hasNext()) {
-        retVal = op.compute(retVal, ((Number) fieldsIter.next().compute(values)).doubleValue());
+        nextVal = (Number) fieldsIter.next().compute(values);
+        if (nextVal == null) {
+          // As per SQL standard if any of the value is null, arithmetic operators will return null.
+          return null;
+        }
+        retVal = op.compute(retVal, (nextVal).doubleValue());
       }
     }
     return retVal;
@@ -268,7 +279,7 @@ public class ArithmeticPostAggregator implements PostAggregator
     /**
      * Ensures the following order: numeric > NaN > Infinite.
      *
-     * The name may be referenced via Ordering.valueOf(String) in the constructor {@link
+     * The name may be referenced via {@link #valueOf(String)} in the constructor {@link
      * ArithmeticPostAggregator#ArithmeticPostAggregator(String, String, List, String)}.
      */
     @SuppressWarnings("unused")

processing/src/main/java/io/druid/query/aggregation/post/DoubleGreatestPostAggregator.java

@@ -23,6 +23,7 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Sets;
+import io.druid.common.config.NullHandling;
 import io.druid.query.Queries;
 import io.druid.query.aggregation.AggregatorFactory;
 import io.druid.query.aggregation.PostAggregator;
@@ -37,14 +38,9 @@ import java.util.Set;
 
 public class DoubleGreatestPostAggregator implements PostAggregator
 {
-  private static final Comparator COMPARATOR = new Comparator()
+  private static final Comparator<Number> COMPARATOR = Comparator.nullsFirst(
-  {
+      Comparator.comparingDouble(Number::doubleValue)
-    @Override
+  );
-    public int compare(Object o, Object o1)
-    {
-      return ((Double) o).compareTo((Double) o1);
-    }
-  };
 
   private final String name;
   private final List<PostAggregator> fields;
@@ -81,13 +77,15 @@ public class DoubleGreatestPostAggregator implements PostAggregator
   public Object compute(Map<String, Object> values)
   {
     Iterator<PostAggregator> fieldsIter = fields.iterator();
-    double retVal = Double.NEGATIVE_INFINITY;
+    Double retVal = NullHandling.replaceWithDefault() ? Double.NEGATIVE_INFINITY : null;
-    if (fieldsIter.hasNext()) {
-      retVal = ((Number) fieldsIter.next().compute(values)).doubleValue();
     while (fieldsIter.hasNext()) {
-        double other = ((Number) fieldsIter.next().compute(values)).doubleValue();
+      Number nextVal = ((Number) fieldsIter.next().compute(values));
-        if (other > retVal) {
+      // Ignore NULL values and return the greatest out of non-null values.
-          retVal = other;
+      if (nextVal != null && (retVal == null || COMPARATOR.compare(nextVal, retVal) > 0)) {
+        if (nextVal instanceof Double) {
+          retVal = (Double) nextVal;
+        } else {
+          retVal = nextVal.doubleValue();
         }
       }
     }

processing/src/main/java/io/druid/query/aggregation/post/DoubleLeastPostAggregator.java

@@ -23,6 +23,7 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Sets;
+import io.druid.common.config.NullHandling;
 import io.druid.query.Queries;
 import io.druid.query.aggregation.AggregatorFactory;
 import io.druid.query.aggregation.PostAggregator;
@@ -37,14 +38,9 @@ import java.util.Set;
 
 public class DoubleLeastPostAggregator implements PostAggregator
 {
-  private static final Comparator COMPARATOR = new Comparator()
+  private static final Comparator<Number> COMPARATOR = Comparator.nullsLast(
-  {
+      Comparator.comparingDouble(Number::doubleValue)
-    @Override
+  );
-    public int compare(Object o, Object o1)
-    {
-      return ((Double) o).compareTo((Double) o1);
-    }
-  };
 
   private final String name;
   private final List<PostAggregator> fields;
@@ -81,13 +77,15 @@ public class DoubleLeastPostAggregator implements PostAggregator
   public Object compute(Map<String, Object> values)
   {
     Iterator<PostAggregator> fieldsIter = fields.iterator();
-    double retVal = Double.POSITIVE_INFINITY;
+    Double retVal = NullHandling.replaceWithDefault() ? Double.POSITIVE_INFINITY : null;
-    if (fieldsIter.hasNext()) {
-      retVal = ((Number) fieldsIter.next().compute(values)).doubleValue();
     while (fieldsIter.hasNext()) {
-        double other = ((Number) fieldsIter.next().compute(values)).doubleValue();
+      Number nextVal = ((Number) fieldsIter.next().compute(values));
-        if (other < retVal) {
+      // Ignore NULL values and return the greatest out of non-null values.
-          retVal = other;
+      if (nextVal != null && (retVal == null || COMPARATOR.compare(nextVal, retVal) < 0)) {
+        if (nextVal instanceof Double) {
+          retVal = (Double) nextVal;
+        } else {
+          retVal = nextVal.doubleValue();
         }
       }
     }

processing/src/main/java/io/druid/query/aggregation/post/LongGreatestPostAggregator.java

@@ -23,7 +23,7 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Sets;
-import com.google.common.primitives.Longs;
+import io.druid.common.config.NullHandling;
 import io.druid.query.Queries;
 import io.druid.query.aggregation.AggregatorFactory;
 import io.druid.query.aggregation.PostAggregator;
@@ -38,14 +38,9 @@ import java.util.Set;
 
 public class LongGreatestPostAggregator implements PostAggregator
 {
-  private static final Comparator COMPARATOR = new Comparator()
+  private static final Comparator<Number> COMPARATOR = Comparator.nullsFirst(
-  {
+      Comparator.comparingLong(Number::longValue)
-    @Override
+  );
-    public int compare(Object o, Object o1)
-    {
-      return Longs.compare(((Number) o).longValue(), ((Number) o1).longValue());
-    }
-  };
 
   private final String name;
   private final List<PostAggregator> fields;
@@ -82,13 +77,15 @@ public class LongGreatestPostAggregator implements PostAggregator
   public Object compute(Map<String, Object> values)
   {
     Iterator<PostAggregator> fieldsIter = fields.iterator();
-    long retVal = Long.MIN_VALUE;
+    Long retVal = NullHandling.replaceWithDefault() ? Long.MIN_VALUE : null;
-    if (fieldsIter.hasNext()) {
-      retVal = ((Number) fieldsIter.next().compute(values)).longValue();
     while (fieldsIter.hasNext()) {
-        long other = ((Number) fieldsIter.next().compute(values)).longValue();
+      Number nextVal = ((Number) fieldsIter.next().compute(values));
-        if (other > retVal) {
+      // Ignore NULL values and return the greatest out of non-null values.
-          retVal = other;
+      if (nextVal != null && (retVal == null || COMPARATOR.compare(nextVal, retVal) > 0)) {
+        if (nextVal instanceof Long) {
+          retVal = (Long) nextVal;
+        } else {
+          retVal = nextVal.longValue();
         }
       }
     }

processing/src/main/java/io/druid/query/aggregation/post/LongLeastPostAggregator.java

@@ -23,7 +23,7 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Sets;
-import com.google.common.primitives.Longs;
+import io.druid.common.config.NullHandling;
 import io.druid.query.Queries;
 import io.druid.query.aggregation.AggregatorFactory;
 import io.druid.query.aggregation.PostAggregator;
@@ -38,14 +38,9 @@ import java.util.Set;
 
 public class LongLeastPostAggregator implements PostAggregator
 {
-  private static final Comparator COMPARATOR = new Comparator()
+  private static final Comparator<Number> COMPARATOR = Comparator.nullsLast(
-  {
+      Comparator.comparingLong(Number::longValue)
-    @Override
+  );
-    public int compare(Object o, Object o1)
-    {
-      return Longs.compare(((Number) o).longValue(), ((Number) o1).longValue());
-    }
-  };
 
   private final String name;
   private final List<PostAggregator> fields;
@@ -82,13 +77,15 @@ public class LongLeastPostAggregator implements PostAggregator
   public Object compute(Map<String, Object> values)
   {
     Iterator<PostAggregator> fieldsIter = fields.iterator();
-    long retVal = Long.MAX_VALUE;
+    Long retVal = NullHandling.replaceWithDefault() ? Long.MAX_VALUE : null;
-    if (fieldsIter.hasNext()) {
-      retVal = ((Number) fieldsIter.next().compute(values)).longValue();
     while (fieldsIter.hasNext()) {
-        long other = ((Number) fieldsIter.next().compute(values)).longValue();
+      Number nextVal = ((Number) fieldsIter.next().compute(values));
-        if (other < retVal) {
+      // Ignore NULL values and return the greatest out of non-null values.
-          retVal = other;
+      if (nextVal != null && (retVal == null || COMPARATOR.compare(nextVal, retVal) < 0)) {
+        if (nextVal instanceof Long) {
+          retVal = (Long) nextVal;
+        } else {
+          retVal = nextVal.longValue();
         }
       }
     }

processing/src/main/java/io/druid/query/dimension/ListFilteredDimensionSpec.java

@@ -23,7 +23,7 @@ import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.common.base.Preconditions;
 import com.google.common.base.Predicate;
 import com.google.common.base.Predicates;
-import com.google.common.base.Strings;
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.StringUtils;
 import io.druid.query.filter.DimFilterUtils;
 import io.druid.segment.DimensionSelector;
@@ -106,7 +106,7 @@ public class ListFilteredDimensionSpec extends BaseFilteredDimensionSpec
       }
     } else {
       for (int i = 0; i < selectorCardinality; i++) {
-        if (values.contains(Strings.nullToEmpty(selector.lookupName(i)))) {
+        if (values.contains(NullHandling.nullToEmptyIfNeeded(selector.lookupName(i)))) {
           forwardMapping.put(i, count);
           reverseMapping[count++] = i;
         }
@@ -137,7 +137,7 @@ public class ListFilteredDimensionSpec extends BaseFilteredDimensionSpec
     forwardMapping.defaultReturnValue(-1);
     final int[] reverseMapping = new int[maxPossibleFilteredCardinality];
     for (int i = 0; i < selectorCardinality; i++) {
-      if (!values.contains(Strings.nullToEmpty(selector.lookupName(i)))) {
+      if (!values.contains(NullHandling.nullToEmptyIfNeeded(selector.lookupName(i)))) {
         forwardMapping.put(i, count);
         reverseMapping[count++] = i;
       }

processing/src/main/java/io/druid/query/dimension/RegexFilteredDimensionSpec.java

@@ -22,7 +22,7 @@ package io.druid.query.dimension;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.common.base.Preconditions;
 import com.google.common.base.Predicate;
-import com.google.common.base.Strings;
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.StringUtils;
 import io.druid.query.filter.DimFilterUtils;
 import io.druid.segment.DimensionSelector;
@@ -76,7 +76,7 @@ public class RegexFilteredDimensionSpec extends BaseFilteredDimensionSpec
             @Override
             public boolean apply(@Nullable String input)
             {
-              return compiledRegex.matcher(Strings.nullToEmpty(input)).matches();
+              return compiledRegex.matcher(NullHandling.nullToEmptyIfNeeded(input)).matches();
             }
           }
       );
@@ -86,7 +86,8 @@ public class RegexFilteredDimensionSpec extends BaseFilteredDimensionSpec
     final Int2IntOpenHashMap forwardMapping = new Int2IntOpenHashMap();
     forwardMapping.defaultReturnValue(-1);
     for (int i = 0; i < selectorCardinality; i++) {
-      if (compiledRegex.matcher(Strings.nullToEmpty(selector.lookupName(i))).matches()) {
+      String val = NullHandling.nullToEmptyIfNeeded(selector.lookupName(i));
+      if (val != null && compiledRegex.matcher(val).matches()) {
         forwardMapping.put(i, count++);
       }
     }

processing/src/main/java/io/druid/query/expression/ExprUtils.java

@@ -19,6 +19,7 @@
 
 package io.druid.query.expression;
 
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.DateTimes;
 import io.druid.java.util.common.IAE;
 import io.druid.java.util.common.granularity.PeriodGranularity;
@@ -73,8 +74,15 @@ public class ExprUtils
     } else {
       Chronology chronology = timeZone == null ? ISOChronology.getInstanceUTC() : ISOChronology.getInstance(timeZone);
       final Object value = originArg.eval(bindings).value();
+      if (value instanceof String && NullHandling.isNullOrEquivalent((String) value)) {
+        // We get a blank string here, when sql compatible null handling is enabled
+        // and expression contains empty string for for origin
+        // e.g timestamp_floor(\"__time\",'PT1M','','UTC')
+        origin = null;
+      } else {
         origin = value != null ? new DateTime(value, chronology) : null;
       }
+    }
 
     return new PeriodGranularity(period, origin, timeZone);
   }

processing/src/main/java/io/druid/query/expression/LikeExprMacro.java

@@ -19,7 +19,7 @@
 
 package io.druid.query.expression;
 
-import com.google.common.base.Strings;
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.IAE;
 import io.druid.math.expr.Expr;
 import io.druid.math.expr.ExprEval;
@@ -63,7 +63,7 @@ public class LikeExprMacro implements ExprMacroTable.ExprMacro
     }
 
     final LikeDimFilter.LikeMatcher likeMatcher = LikeDimFilter.LikeMatcher.from(
-        Strings.nullToEmpty((String) patternExpr.getLiteralValue()),
+        NullHandling.nullToEmptyIfNeeded((String) patternExpr.getLiteralValue()),
         escapeChar
     );
 

processing/src/main/java/io/druid/query/expression/RegexpExtractExprMacro.java

@@ -19,7 +19,7 @@
 
 package io.druid.query.expression;
 
-import com.google.common.base.Strings;
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.IAE;
 import io.druid.math.expr.Expr;
 import io.druid.math.expr.ExprEval;
@@ -63,9 +63,10 @@ public class RegexpExtractExprMacro implements ExprMacroTable.ExprMacro
       @Override
       public ExprEval eval(final ObjectBinding bindings)
       {
-        final Matcher matcher = pattern.matcher(Strings.nullToEmpty(arg.eval(bindings).asString()));
+        String s = arg.eval(bindings).asString();
+        final Matcher matcher = pattern.matcher(NullHandling.nullToEmptyIfNeeded(s));
         final String retVal = matcher.find() ? matcher.group(index) : null;
-        return ExprEval.of(Strings.emptyToNull(retVal));
+        return ExprEval.of(NullHandling.emptyToNullIfNeeded(retVal));
       }
 
       @Override

processing/src/main/java/io/druid/query/expression/TimestampCeilExprMacro.java

@@ -67,6 +67,11 @@ public class TimestampCeilExprMacro implements ExprMacroTable.ExprMacro
     @Override
     public ExprEval eval(final ObjectBinding bindings)
     {
+      ExprEval eval = arg.eval(bindings);
+      if (eval.isNumericNull()) {
+        // Return null if the argument if null.
+        return ExprEval.of(null);
+      }
       return ExprEval.of(granularity.bucketEnd(DateTimes.utc(arg.eval(bindings).asLong())).getMillis());
     }
 

processing/src/main/java/io/druid/query/expression/TimestampExtractExprMacro.java

@@ -88,7 +88,12 @@ public class TimestampExtractExprMacro implements ExprMacroTable.ExprMacro
       @Override
       public ExprEval eval(final ObjectBinding bindings)
       {
-        final DateTime dateTime = new DateTime(arg.eval(bindings).asLong(), chronology);
+        Object val = arg.eval(bindings).value();
+        if (val == null) {
+          // Return null if the argument if null.
+          return ExprEval.of(null);
+        }
+        final DateTime dateTime = new DateTime(val, chronology);
         switch (unit) {
           case EPOCH:
             return ExprEval.of(dateTime.getMillis() / 1000);

processing/src/main/java/io/druid/query/expression/TimestampFloorExprMacro.java

@@ -92,7 +92,12 @@ public class TimestampFloorExprMacro implements ExprMacroTable.ExprMacro
     @Override
     public ExprEval eval(final ObjectBinding bindings)
     {
-      return ExprEval.of(granularity.bucketStart(DateTimes.utc(arg.eval(bindings).asLong())).getMillis());
+      ExprEval eval = arg.eval(bindings);
+      if (eval.isNumericNull()) {
+        // Return null if the argument if null.
+        return ExprEval.of(null);
+      }
+      return ExprEval.of(granularity.bucketStart(DateTimes.utc(eval.asLong())).getMillis());
     }
 
     @Override

processing/src/main/java/io/druid/query/expression/TimestampFormatExprMacro.java

@@ -74,6 +74,11 @@ public class TimestampFormatExprMacro implements ExprMacroTable.ExprMacro
       @Override
       public ExprEval eval(final ObjectBinding bindings)
       {
+        ExprEval eval = arg.eval(bindings);
+        if (eval.isNumericNull()) {
+          // Return null if the argument if null.
+          return ExprEval.of(null);
+        }
         return ExprEval.of(formatter.print(arg.eval(bindings).asLong()));
       }
 

processing/src/main/java/io/druid/query/expression/TrimExprMacro.java

@@ -113,7 +113,7 @@ public abstract class TrimExprMacro implements ExprMacroTable.ExprMacro
     {
       final ExprEval stringEval = stringExpr.eval(bindings);
 
-      if (chars.length == 0 || stringEval.isNull()) {
+      if (chars.length == 0 || stringEval.value() == null) {
         return stringEval;
       }
 
@@ -176,13 +176,13 @@ public abstract class TrimExprMacro implements ExprMacroTable.ExprMacro
     {
       final ExprEval stringEval = stringExpr.eval(bindings);
 
-      if (stringEval.isNull()) {
+      if (stringEval.value() == null) {
         return stringEval;
       }
 
       final ExprEval charsEval = charsExpr.eval(bindings);
 
-      if (charsEval.isNull()) {
+      if (charsEval.value() == null) {
         return stringEval;
       }
 

processing/src/main/java/io/druid/query/extraction/FunctionalExtraction.java

@@ -21,7 +21,7 @@ package io.druid.query.extraction;
 
 import com.google.common.base.Function;
 import com.google.common.base.Preconditions;
-import com.google.common.base.Strings;
+import io.druid.common.config.NullHandling;
 
 import javax.annotation.Nullable;
 
@@ -52,9 +52,9 @@ public abstract class FunctionalExtraction extends DimExtractionFn
   )
   {
     this.retainMissingValue = retainMissingValue;
-    this.replaceMissingValueWith = Strings.emptyToNull(replaceMissingValueWith);
+    this.replaceMissingValueWith = NullHandling.emptyToNullIfNeeded(replaceMissingValueWith);
     Preconditions.checkArgument(
-        !(this.retainMissingValue && !Strings.isNullOrEmpty(this.replaceMissingValueWith)),
+        !(this.retainMissingValue && !(this.replaceMissingValueWith == null)),
         "Cannot specify a [replaceMissingValueWith] and set [retainMissingValue] to true"
     );
 
@@ -69,7 +69,7 @@ public abstract class FunctionalExtraction extends DimExtractionFn
         public String apply(@Nullable String dimValue)
         {
           final String retval = extractionFunction.apply(dimValue);
-          return Strings.isNullOrEmpty(retval) ? Strings.emptyToNull(dimValue) : retval;
+          return NullHandling.isNullOrEquivalent(retval) ? NullHandling.emptyToNullIfNeeded(dimValue) : retval;
         }
       };
     } else {
@@ -79,8 +79,10 @@ public abstract class FunctionalExtraction extends DimExtractionFn
         @Override
         public String apply(@Nullable String dimValue)
         {
-          final String retval = extractionFunction.apply(dimValue);
+          final String retval = NullHandling.emptyToNullIfNeeded(extractionFunction.apply(dimValue));
-          return Strings.isNullOrEmpty(retval) ? FunctionalExtraction.this.replaceMissingValueWith : retval;
+          return retval == null
+                 ? FunctionalExtraction.this.replaceMissingValueWith
+                 : retval;
         }
       };
     }

processing/src/main/java/io/druid/query/extraction/IdentityExtractionFn.java

@@ -19,7 +19,7 @@
 
 package io.druid.query.extraction;
 
-import com.google.common.base.Strings;
+import io.druid.common.config.NullHandling;
 
 import javax.annotation.Nullable;
 
@@ -42,14 +42,14 @@ public class IdentityExtractionFn implements ExtractionFn
   @Nullable
   public String apply(@Nullable Object value)
   {
-    return value == null ? null : Strings.emptyToNull(value.toString());
+    return value == null ? null : NullHandling.emptyToNullIfNeeded(value.toString());
   }
 
   @Override
   @Nullable
   public String apply(@Nullable String value)
   {
-    return Strings.emptyToNull(value);
+    return NullHandling.emptyToNullIfNeeded(value);
   }
 
   @Override

processing/src/main/java/io/druid/query/extraction/JavaScriptExtractionFn.java

@@ -24,7 +24,7 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.common.base.Function;
 import com.google.common.base.Preconditions;
-import com.google.common.base.Strings;
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.StringUtils;
 import io.druid.js.JavaScriptConfig;
 import org.mozilla.javascript.Context;
@@ -113,7 +113,7 @@ public class JavaScriptExtractionFn implements ExtractionFn
   public String apply(@Nullable Object value)
   {
     checkAndCompileScript();
-    return Strings.emptyToNull(fn.apply(value));
+    return NullHandling.emptyToNullIfNeeded(fn.apply(value));
   }
 
   /**
@@ -139,7 +139,7 @@ public class JavaScriptExtractionFn implements ExtractionFn
   @Nullable
   public String apply(@Nullable String value)
   {
-    return this.apply((Object) Strings.emptyToNull(value));
+    return this.apply((Object) NullHandling.emptyToNullIfNeeded(value));
   }
 
   @Override

processing/src/main/java/io/druid/query/extraction/LowerExtractionFn.java

@@ -21,7 +21,7 @@ package io.druid.query.extraction;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonTypeName;
-import com.google.common.base.Strings;
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.StringUtils;
 
 import javax.annotation.Nullable;
@@ -52,7 +52,7 @@ public class LowerExtractionFn extends DimExtractionFn
   @Override
   public String apply(@Nullable String key)
   {
-    if (Strings.isNullOrEmpty(key)) {
+    if (NullHandling.isNullOrEquivalent(key)) {
       return null;
     }
     return key.toLowerCase(locale);
@@ -73,7 +73,7 @@ public class LowerExtractionFn extends DimExtractionFn
   @Override
   public byte[] getCacheKey()
   {
-    byte[] localeBytes = StringUtils.toUtf8(Strings.nullToEmpty(localeString));
+    byte[] localeBytes = StringUtils.toUtf8(StringUtils.nullToEmptyNonDruidDataString(localeString));
     return ByteBuffer.allocate(2 + localeBytes.length)
                      .put(ExtractionCacheHelper.CACHE_TYPE_ID_LOWER)
                      .put((byte) 0XFF)

processing/src/main/java/io/druid/query/extraction/MapLookupExtractor.java

@@ -23,21 +23,20 @@ import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonTypeName;
 import com.google.common.base.Preconditions;
-import com.google.common.base.Predicate;
 import com.google.common.base.Strings;
 import com.google.common.base.Throwables;
 import com.google.common.collect.ImmutableMap;
-import com.google.common.collect.Lists;
+import io.druid.common.config.NullHandling;
-import com.google.common.collect.Maps;
 import io.druid.java.util.common.StringUtils;
 import io.druid.query.lookup.LookupExtractor;
 
 import javax.annotation.Nullable;
-import javax.validation.constraints.NotNull;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
+import java.util.stream.Collectors;
 
 @JsonTypeName("map")
 public class MapLookupExtractor extends LookupExtractor
@@ -64,22 +63,32 @@ public class MapLookupExtractor extends LookupExtractor
 
   @Nullable
   @Override
-  public String apply(@NotNull String val)
+  public String apply(@Nullable String key)
   {
-    return map.get(val);
+    String keyEquivalent = NullHandling.nullToEmptyIfNeeded(key);
+    if (keyEquivalent == null) {
+      // keyEquivalent is null only for SQL Compatible Null Behavior
+      // otherwise null will be replaced with empty string in nullToEmptyIfNeeded above.
+      return null;
+    }
+    return NullHandling.emptyToNullIfNeeded(map.get(keyEquivalent));
   }
 
   @Override
-  public List<String> unapply(final String value)
+  public List<String> unapply(@Nullable final String value)
   {
-    return Lists.newArrayList(Maps.filterKeys(map, new Predicate<String>()
+    String valueToLookup = NullHandling.nullToEmptyIfNeeded(value);
-    {
+    if (valueToLookup == null) {
-      @Override public boolean apply(@Nullable String key)
+      // valueToLookup is null only for SQL Compatible Null Behavior
-      {
+      // otherwise null will be replaced with empty string in nullToEmptyIfNeeded above.
-        return map.get(key).equals(Strings.nullToEmpty(value));
+      // null value maps to empty list when SQL Compatible
+      return Collections.emptyList();
     }
-    }).keySet());
+    return map.entrySet()
-
+              .stream()
+              .filter(entry -> entry.getValue().equals(valueToLookup))
+              .map(entry -> entry.getKey())
+              .collect(Collectors.toList());
   }
 
   @Override

processing/src/main/java/io/druid/query/extraction/MatchingDimExtractionFn.java

@@ -22,7 +22,7 @@ package io.druid.query.extraction;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.google.common.base.Preconditions;
-import com.google.common.base.Strings;
+import io.druid.common.config.NullHandling;
 import io.druid.java.util.common.StringUtils;
 
 import javax.annotation.Nullable;
@@ -62,7 +62,7 @@ public class MatchingDimExtractionFn extends DimExtractionFn
   @Override
   public String apply(@Nullable String dimValue)
   {
-    if (Strings.isNullOrEmpty(dimValue)) {
+    if (NullHandling.isNullOrEquivalent(dimValue)) {
       // We'd return null whether or not the pattern matched
       return null;
     }