Do not use hash-based collections in aggregates

h2/src/main/org/h2/expression/aggregate/Aggregate.java

@@ -10,6 +10,7 @@ import java.util.Arrays;
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.Map.Entry;
+import java.util.TreeMap;
 import org.h2.api.ErrorCode;
 import org.h2.command.dml.Select;
 import org.h2.command.dml.SelectOrderBy;
@@ -32,7 +33,6 @@ import org.h2.table.ColumnResolver;
 import org.h2.table.Table;
 import org.h2.table.TableFilter;
 import org.h2.util.StatementBuilder;
-import org.h2.util.ValueHashMap;
 import org.h2.value.CompareMode;
 import org.h2.value.DataType;
 import org.h2.value.TypeInfo;
@@ -512,13 +512,13 @@ public class Aggregate extends AbstractAggregate {
     }
 
     private Value getHistogram(Session session, AggregateData data) {
-        ValueHashMap<LongDataCounter> distinctValues = ((AggregateDataDistinctWithCounts) data).getValues();
+        TreeMap<Value, LongDataCounter> distinctValues = ((AggregateDataDistinctWithCounts) data).getValues();
         if (distinctValues == null) {
             return ValueArray.getEmpty();
         }
         ValueArray[] values = new ValueArray[distinctValues.size()];
         int i = 0;
-        for (Entry<Value, LongDataCounter> entry : distinctValues.entries()) {
+        for (Entry<Value, LongDataCounter> entry : distinctValues.entrySet()) {
             LongDataCounter d = entry.getValue();
             values[i] = ValueArray.get(new Value[] { entry.getKey(), ValueLong.get(distinct ? 1L : d.count) });
             i++;
@@ -539,14 +539,14 @@ public class Aggregate extends AbstractAggregate {
 
     private Value getMode(Session session, AggregateData data) {
         Value v = ValueNull.INSTANCE;
-        ValueHashMap<LongDataCounter> distinctValues = ((AggregateDataDistinctWithCounts) data).getValues();
+        TreeMap<Value, LongDataCounter> distinctValues = ((AggregateDataDistinctWithCounts) data).getValues();
         if (distinctValues == null) {
             return v;
         }
         long count = 0L;
         if (orderByList != null) {
             boolean desc = (orderByList.get(0).sortType & SortOrder.DESCENDING) != 0;
-            for (Entry<Value, LongDataCounter> entry : distinctValues.entries()) {
+            for (Entry<Value, LongDataCounter> entry : distinctValues.entrySet()) {
                 long c = entry.getValue().count;
                 if (c > count) {
                     v = entry.getKey();
@@ -565,7 +565,7 @@ public class Aggregate extends AbstractAggregate {
                 }
             }
         } else {
-            for (Entry<Value, LongDataCounter> entry : distinctValues.entries()) {
+            for (Entry<Value, LongDataCounter> entry : distinctValues.entrySet()) {
                 long c = entry.getValue().count;
                 if (c > count) {
                     v = entry.getKey();

h2/src/main/org/h2/expression/aggregate/AggregateDataCollecting.java

@@ -8,8 +8,8 @@ package org.h2.expression.aggregate;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
-import java.util.HashSet;
 import java.util.Iterator;
+import java.util.TreeSet;
 
 import org.h2.engine.Database;
 import org.h2.value.Value;
@@ -47,7 +47,7 @@ class AggregateDataCollecting extends AggregateData implements Iterable<Value> {
         }
         Collection<Value> c = values;
         if (c == null) {
-            values = c = distinct ? new HashSet<Value>() : new ArrayList<Value>();
+            values = c = distinct ? new TreeSet<>(database.getCompareMode()) : new ArrayList<Value>();
         }
         c.add(v);
     }

h2/src/main/org/h2/expression/aggregate/AggregateDataDistinctWithCounts.java

@@ -5,8 +5,8 @@
  */
 package org.h2.expression.aggregate;
 
+import java.util.TreeMap;
 import org.h2.engine.Database;
-import org.h2.util.ValueHashMap;
 import org.h2.value.Value;
 import org.h2.value.ValueNull;
 
@@ -20,7 +20,7 @@ class AggregateDataDistinctWithCounts extends AggregateData {
 
     private final int maxDistinctCount;
 
-    private ValueHashMap<LongDataCounter> values;
+    private TreeMap<Value, LongDataCounter> values;
 
     /**
      * Creates new instance of data for aggregate that needs distinct values
@@ -42,7 +42,7 @@ class AggregateDataDistinctWithCounts extends AggregateData {
             return;
         }
         if (values == null) {
-            values = new ValueHashMap<>();
+            values = new TreeMap<>(database.getCompareMode());
         }
         LongDataCounter a = values.get(v);
         if (a == null) {
@@ -65,7 +65,7 @@ class AggregateDataDistinctWithCounts extends AggregateData {
      *
      * @return map with values and their counts
      */
-    ValueHashMap<LongDataCounter> getValues() {
+    TreeMap<Value, LongDataCounter> getValues() {
         return values;
     }
 

h2/src/test/org/h2/test/scripts/functions/aggregate/count.sql

@@ -104,3 +104,18 @@ SELECT X, COUNT(*) OVER (ORDER BY X) C FROM VALUES (1), (1), (2), (2), (3) V(X);
 > 2 4
 > 3 5
 > rows: 5
+
+CREATE TABLE TEST (N NUMERIC) AS VALUES (0), (0.0), (NULL);
+> ok
+
+SELECT COUNT(*) FROM TEST;
+>> 3
+
+SELECT COUNT(N) FROM TEST;
+>> 2
+
+SELECT COUNT(DISTINCT N) FROM TEST;
+>> 1
+
+DROP TABLE TEST;
+> ok

h2/src/test/org/h2/test/scripts/functions/aggregate/mode.sql

@@ -57,3 +57,12 @@ SELECT MODE() WITHIN GROUP(ORDER BY V DESC) FROM TEST;
 
 DROP TABLE TEST;
 > ok
+
+CREATE TABLE TEST (N NUMERIC) AS VALUES (0), (0.0), (NULL);
+> ok
+
+SELECT MODE(N) FROM TEST;
+>> 0
+
+DROP TABLE TEST;
+> ok