Merge pull request #579 from citusdata/fix/569_count_distinct_crash

Fix crash in count distinct with filters in repartition subqueries

src/backend/distributed/planner/multi_logical_optimizer.c

@@ -1360,9 +1360,7 @@ MasterAggregateExpression(Aggref *originalAggregate,
 		walkerContext->repartitionSubquery)
 	{
 		Aggref *aggregate = (Aggref *) copyObject(originalAggregate);
-		List *aggTargetEntryList = aggregate->args;
-		TargetEntry *distinctTargetEntry = linitial(aggTargetEntryList);
-		List *varList = pull_var_clause_default((Node *) distinctTargetEntry->expr);
+		List *varList = pull_var_clause_default((Node *) aggregate);
 		ListCell *varCell = NULL;
 		List *uniqueVarList = NIL;
 		int startColumnCount = walkerContext->columnId;
@@ -1878,22 +1876,12 @@ WorkerAggregateExpressionList(Aggref *originalAggregate,
 		walkerContext->repartitionSubquery)
 	{
 		Aggref *aggregate = (Aggref *) copyObject(originalAggregate);
-		List *aggTargetEntryList = aggregate->args;
-		TargetEntry *distinctTargetEntry = (TargetEntry *) linitial(aggTargetEntryList);
-		List *columnList = pull_var_clause_default((Node *) distinctTargetEntry);
+		List *columnList = pull_var_clause_default((Node *) aggregate);
 		ListCell *columnCell = NULL;
-		List *processedColumnList = NIL;
-
 		foreach(columnCell, columnList)
 		{
 			Var *column = (Var *) lfirst(columnCell);
-			if (list_member(processedColumnList, column))
-			{
-				continue;
-			}
-
-			processedColumnList = lappend(processedColumnList, column);
-			workerAggregateList = lappend(workerAggregateList, copyObject(column));
+			workerAggregateList = list_append_unique(workerAggregateList, column);
 		}
 
 		walkerContext->createGroupByClause = true;

src/test/regress/input/multi_complex_count_distinct.source

@@ -76,6 +76,34 @@ SELECT *
 	ORDER BY 2 DESC, 1 DESC
 	LIMIT 10;
 
+-- there is a known issue with aggregates with filters in non-repartition queries (#395)
+SELECT
+	l_orderkey, count(DISTINCT l_partkey) FILTER (WHERE l_shipmode = 'AIR')
+	FROM lineitem_hash
+	GROUP BY l_orderkey
+	ORDER BY 2 DESC, 1 DESC
+	LIMIT 10;
+
+-- filter column already exists in target list
+SELECT *
+	FROM (
+		SELECT
+			l_orderkey, count(DISTINCT l_partkey) FILTER (WHERE l_orderkey > 100)
+			FROM lineitem_hash
+			GROUP BY l_orderkey) sub
+	ORDER BY 2 DESC, 1 DESC
+	LIMIT 10;
+
+-- filter column does not exist in target list
+SELECT *
+	FROM (
+		SELECT
+			l_orderkey, count(DISTINCT l_partkey) FILTER (WHERE l_shipmode = 'AIR')
+			FROM lineitem_hash
+			GROUP BY l_orderkey) sub
+	ORDER BY 2 DESC, 1 DESC
+	LIMIT 10;
+
 -- case expr in count distinct is supported.
 -- count orders partkeys if l_shipmode is air
 SELECT *

src/test/regress/output/multi_complex_count_distinct.source

@@ -122,6 +122,60 @@ SELECT *
       1927 |     3
 (10 rows)
 
+-- there is a known issue with aggregates with filters in non-repartition queries (#395)
+SELECT
+	l_orderkey, count(DISTINCT l_partkey) FILTER (WHERE l_shipmode = 'AIR')
+	FROM lineitem_hash
+	GROUP BY l_orderkey
+	ORDER BY 2 DESC, 1 DESC
+	LIMIT 10;
+ERROR:  attribute number 15 exceeds number of columns 2
+-- filter column already exists in target list
+SELECT *
+	FROM (
+		SELECT
+			l_orderkey, count(DISTINCT l_partkey) FILTER (WHERE l_orderkey > 100)
+			FROM lineitem_hash
+			GROUP BY l_orderkey) sub
+	ORDER BY 2 DESC, 1 DESC
+	LIMIT 10;
+ l_orderkey | count 
+------------+-------
+      14885 |     7
+      14884 |     7
+      14821 |     7
+      14790 |     7
+      14785 |     7
+      14755 |     7
+      14725 |     7
+      14694 |     7
+      14627 |     7
+      14624 |     7
+(10 rows)
+
+-- filter column does not exist in target list
+SELECT *
+	FROM (
+		SELECT
+			l_orderkey, count(DISTINCT l_partkey) FILTER (WHERE l_shipmode = 'AIR')
+			FROM lineitem_hash
+			GROUP BY l_orderkey) sub
+	ORDER BY 2 DESC, 1 DESC
+	LIMIT 10;
+ l_orderkey | count 
+------------+-------
+      12005 |     4
+       5409 |     4
+       4964 |     4
+      14848 |     3
+      14496 |     3
+      13473 |     3
+      13122 |     3
+      12929 |     3
+      12645 |     3
+      12417 |     3
+(10 rows)
+
 -- case expr in count distinct is supported.
 -- count orders partkeys if l_shipmode is air
 SELECT *