Fix error message for groupByEnableMultiValueUnnesting. (#12325)

* Fix error message for groupByEnableMultiValueUnnesting.

It referred to the incorrect context parameter.

Also, create a dedicated exception class, to allow easier detection of this
specific error.

* Fix other test.

* More better error messages.

* Test getDimensionName method.

processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/GroupByMergingQueryRunnerV2.java

@@ -23,6 +23,7 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.common.base.Function;
 import com.google.common.base.Predicates;
 import com.google.common.base.Suppliers;
+import com.google.common.base.Throwables;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
@@ -249,6 +250,7 @@ public class GroupByMergingQueryRunnerV2 implements QueryRunner<ResultRow>
                                       }
                                       catch (Exception e) {
                                         log.error(e, "Exception with one of the sequences!");
+                                        Throwables.propagateIfPossible(e);
                                         throw new RuntimeException(e);
                                       }
                                     }

processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/GroupByQueryEngineV2.java

@@ -599,19 +599,15 @@ public class GroupByQueryEngineV2
       return indexedInts.size() == 1 ? indexedInts.get(0) : GroupByColumnSelectorStrategy.GROUP_BY_MISSING_VALUE;
     }
 
+    /**
+     * Throws {@link UnexpectedMultiValueDimensionException} if "allowMultiValueGrouping" is false.
+     */
     protected void checkIfMultiValueGroupingIsAllowed(String dimName)
     {
       if (!allowMultiValueGrouping) {
-        throw new ISE(
+        throw new UnexpectedMultiValueDimensionException(dimName);
-            "Encountered multi-value dimension %s that cannot be processed with %s set to false."
-            + " Consider setting %s to true.",
-            dimName,
-            GroupByQueryConfig.CTX_KEY_EXECUTING_NESTED_QUERY,
-            GroupByQueryConfig.CTX_KEY_EXECUTING_NESTED_QUERY
-        );
       }
     }
-
   }
 
   private static class HashAggregateIterator extends GroupByEngineIterator<ByteBuffer>

processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/UnexpectedMultiValueDimensionException.java

@@ -0,0 +1,48 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.druid.query.groupby.epinephelinae;
+
+import org.apache.druid.java.util.common.StringUtils;
+import org.apache.druid.query.groupby.GroupByQueryConfig;
+
+public class UnexpectedMultiValueDimensionException extends RuntimeException
+{
+  private final String dimensionName;
+
+  public UnexpectedMultiValueDimensionException(String dimensionName)
+  {
+    super(
+        StringUtils.format(
+            "Encountered multi-value dimension [%s] that cannot be processed with '%s' set to false."
+            + " Consider setting '%s' to true in your query context.",
+            dimensionName,
+            GroupByQueryConfig.CTX_KEY_ENABLE_MULTI_VALUE_UNNESTING,
+            GroupByQueryConfig.CTX_KEY_ENABLE_MULTI_VALUE_UNNESTING
+        )
+    );
+
+    this.dimensionName = dimensionName;
+  }
+
+  public String getDimensionName()
+  {
+    return dimensionName;
+  }
+}

processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/column/ArrayDoubleGroupByColumnSelectorStrategy.java

@@ -24,6 +24,7 @@ import com.google.common.collect.ImmutableList;
 import it.unimi.dsi.fastutil.objects.Object2IntOpenHashMap;
 import org.apache.druid.java.util.common.ISE;
 import org.apache.druid.segment.ColumnValueSelector;
+import org.apache.druid.segment.column.ValueType;
 
 import java.util.Arrays;
 import java.util.List;
@@ -62,7 +63,7 @@ public class ArrayDoubleGroupByColumnSelectorStrategy extends ArrayNumericGroupB
                                           .map(a -> (Double) a)
                                           .collect(Collectors.toList()));
     } else {
-      throw new ISE("Found unknowm type %s in ColumnValueSelector.", object.getClass().toString());
+      throw new ISE("Found unexpected object type [%s] in %s array.", object.getClass().getName(), ValueType.DOUBLE);
     }
   }
 }

processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/column/ArrayLongGroupByColumnSelectorStrategy.java

@@ -24,6 +24,7 @@ import com.google.common.collect.ImmutableList;
 import it.unimi.dsi.fastutil.objects.Object2IntOpenHashMap;
 import org.apache.druid.java.util.common.ISE;
 import org.apache.druid.segment.ColumnValueSelector;
+import org.apache.druid.segment.column.ValueType;
 
 import java.util.Arrays;
 import java.util.List;
@@ -62,7 +63,7 @@ public class ArrayLongGroupByColumnSelectorStrategy extends ArrayNumericGroupByC
                                           .map(a -> (Long) a)
                                           .collect(Collectors.toList()));
     } else {
-      throw new ISE("Found unknowm type %s in ColumnValueSelector.", object.getClass().toString());
+      throw new ISE("Found unexpected object type [%s] in %s array.", object.getClass().getName(), ValueType.LONG);
     }
   }
 }

processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/column/ArrayStringGroupByColumnSelectorStrategy.java

@@ -29,6 +29,7 @@ import org.apache.druid.query.groupby.epinephelinae.Grouper;
 import org.apache.druid.query.ordering.StringComparator;
 import org.apache.druid.query.ordering.StringComparators;
 import org.apache.druid.segment.ColumnValueSelector;
+import org.apache.druid.segment.column.ValueType;
 import org.apache.druid.segment.data.ComparableIntArray;
 import org.apache.druid.segment.data.ComparableStringArray;
 
@@ -173,7 +174,7 @@ public class ArrayStringGroupByColumnSelectorStrategy implements GroupByColumnSe
         intRepresentation[i] = addToIndexedDictionary((String) ((Object[]) object)[i]);
       }
     } else {
-      throw new ISE("Found unknowm type %s in ColumnValueSelector.", object.getClass().toString());
+      throw new ISE("Found unexpected object type [%s] in %s array.", object.getClass().getName(), ValueType.STRING);
     }
 
     final ComparableIntArray comparableIntArray = ComparableIntArray.of(intRepresentation);

processing/src/test/java/org/apache/druid/query/groupby/GroupByQueryRunnerTest.java

@@ -114,6 +114,7 @@ import org.apache.druid.query.filter.OrDimFilter;
 import org.apache.druid.query.filter.RegexDimFilter;
 import org.apache.druid.query.filter.SearchQueryDimFilter;
 import org.apache.druid.query.filter.SelectorDimFilter;
+import org.apache.druid.query.groupby.epinephelinae.UnexpectedMultiValueDimensionException;
 import org.apache.druid.query.groupby.having.DimFilterHavingSpec;
 import org.apache.druid.query.groupby.having.DimensionSelectorHavingSpec;
 import org.apache.druid.query.groupby.having.EqualToHavingSpec;
@@ -137,6 +138,9 @@ import org.apache.druid.segment.data.ComparableList;
 import org.apache.druid.segment.data.ComparableStringArray;
 import org.apache.druid.segment.virtual.ExpressionVirtualColumn;
 import org.apache.druid.testing.InitializedNullHandlingTest;
+import org.hamcrest.BaseMatcher;
+import org.hamcrest.CoreMatchers;
+import org.hamcrest.Description;
 import org.joda.time.DateTime;
 import org.joda.time.DateTimeZone;
 import org.joda.time.Period;
@@ -145,6 +149,7 @@ import org.junit.Assert;
 import org.junit.Ignore;
 import org.junit.Rule;
 import org.junit.Test;
+import org.junit.internal.matchers.ThrowableCauseMatcher;
 import org.junit.rules.ExpectedException;
 import org.junit.runner.RunWith;
 import org.junit.runners.Parameterized;
@@ -160,6 +165,7 @@ import java.util.HashMap;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 
@@ -1321,6 +1327,7 @@ public class GroupByQueryRunnerTest extends InitializedNullHandlingTest
   @Test
   public void testMultiValueDimensionNotAllowed()
   {
+    final String dimName = "placementish";
 
     if (config.getDefaultStrategy().equals(GroupByStrategySelector.STRATEGY_V1)) {
       expectedException.expect(UOE.class);
@@ -1330,13 +1337,38 @@ public class GroupByQueryRunnerTest extends InitializedNullHandlingTest
       ));
     } else if (!vectorize) {
       expectedException.expect(RuntimeException.class);
-      expectedException.expectMessage(StringUtils.format(
+      expectedException.expectCause(CoreMatchers.instanceOf(ExecutionException.class));
-          "Encountered multi-value dimension %s that cannot be processed with %s set to false."
+      expectedException.expectCause(
-          + " Consider setting %s to true.",
+          ThrowableCauseMatcher.hasCause(CoreMatchers.instanceOf(UnexpectedMultiValueDimensionException.class))
-          "placementish",
+      );
-          GroupByQueryConfig.CTX_KEY_EXECUTING_NESTED_QUERY,
+      expectedException.expect(
-          GroupByQueryConfig.CTX_KEY_EXECUTING_NESTED_QUERY
+          new BaseMatcher<Throwable>()
-      ));
+          {
+            @Override
+            public boolean matches(Object o)
+            {
+              final UnexpectedMultiValueDimensionException cause =
+                  (UnexpectedMultiValueDimensionException) ((Throwable) o).getCause().getCause();
+
+              return dimName.equals(cause.getDimensionName());
+            }
+
+            @Override
+            public void describeTo(Description description)
+            {
+              description.appendText("an UnexpectedMultiValueDimensionException with dimension [placementish]");
+            }
+          }
+      );
+      expectedException.expectMessage(
+          StringUtils.format(
+              "Encountered multi-value dimension [%s] that cannot be processed with '%s' set to false."
+              + " Consider setting '%s' to true in your query context.",
+              dimName,
+              GroupByQueryConfig.CTX_KEY_ENABLE_MULTI_VALUE_UNNESTING,
+              GroupByQueryConfig.CTX_KEY_ENABLE_MULTI_VALUE_UNNESTING
+          )
+      );
     } else {
       cannotVectorize();
     }
@@ -1344,7 +1376,7 @@ public class GroupByQueryRunnerTest extends InitializedNullHandlingTest
     GroupByQuery query = makeQueryBuilder()
         .setDataSource(QueryRunnerTestHelper.DATA_SOURCE)
         .setQuerySegmentSpec(QueryRunnerTestHelper.FIRST_TO_THIRD)
-        .setDimensions(new DefaultDimensionSpec("placementish", "alias"))
+        .setDimensions(new DefaultDimensionSpec(dimName, "alias"))
         .setAggregatorSpecs(QueryRunnerTestHelper.ROWS_COUNT, new LongSumAggregatorFactory("idx", "index"))
         .setGranularity(QueryRunnerTestHelper.ALL_GRAN)
         .overrideContext(ImmutableMap.of(GroupByQueryConfig.CTX_KEY_ENABLE_MULTI_VALUE_UNNESTING, false))

sql/src/test/java/org/apache/druid/sql/calcite/CalciteMultiValueStringQueryTest.java

@@ -123,11 +123,11 @@ public class CalciteMultiValueStringQueryTest extends BaseCalciteQueryTest
         exception -> {
           exception.expect(RuntimeException.class);
           expectedException.expectMessage(StringUtils.format(
-              "Encountered multi-value dimension %s that cannot be processed with %s set to false."
+              "Encountered multi-value dimension [%s] that cannot be processed with '%s' set to false."
-              + " Consider setting %s to true.",
+              + " Consider setting '%s' to true in your query context.",
               "v0",
-              GroupByQueryConfig.CTX_KEY_EXECUTING_NESTED_QUERY,
+              GroupByQueryConfig.CTX_KEY_ENABLE_MULTI_VALUE_UNNESTING,
-              GroupByQueryConfig.CTX_KEY_EXECUTING_NESTED_QUERY
+              GroupByQueryConfig.CTX_KEY_ENABLE_MULTI_VALUE_UNNESTING
           ));
         }
     );