Use TreeMap in SelectGroups

h2/src/main/org/h2/command/dml/SelectGroups.java

@@ -51,7 +51,7 @@ public abstract class SelectGroups {
         /**
          * Map of group-by key to group-by expression data e.g. AggregateData
          */
-        private HashMap<ValueArray, Object[]> groupByData;
+        private TreeMap<ValueArray, Object[]> groupByData;
 
         /**
          * Key into groupByData that produces currentGroupByExprData. Not used
@@ -72,7 +72,7 @@ public abstract class SelectGroups {
         @Override
         public void reset() {
             super.reset();
-            groupByData = new HashMap<>();
+            groupByData = new TreeMap<>(session.getDatabase().getCompareMode());
             currentGroupsKey = null;
             cursor = null;
         }

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

@@ -117,6 +117,13 @@ SELECT COUNT(N) FROM TEST;
 SELECT COUNT(DISTINCT N) FROM TEST;
 >> 1
 
+SELECT COUNT(*) FROM TEST GROUP BY N;
+> COUNT(*)
+> --------
+> 1
+> 2
+> rows: 2
+
 SELECT COUNT(N) OVER (PARTITION BY N) C FROM TEST;
 > C
 > -