Implement the FILTER clause for aggregate function calls.

This is SQL-standard with a few extensions, namely support for
subqueries and outer references in clause expressions.

catversion bump due to change in Aggref and WindowFunc.

David Fetter, reviewed by Dean Rasheed.

1 files changed, 14 insertions, 0 deletions

diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index d9f0e79d10..bbc53361d6 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -227,9 +227,23 @@ advance_windowaggregate(WindowAggState *winstate,
 	int			i;
 	MemoryContext oldContext;
 	ExprContext *econtext = winstate->tmpcontext;
+	ExprState  *filter = wfuncstate->aggfilter;
 
 	oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
 
+	/* Skip anything FILTERed out */
+	if (filter)
+	{
+		bool		isnull;
+		Datum		res = ExecEvalExpr(filter, econtext, &isnull, NULL);
+
+		if (isnull || !DatumGetBool(res))
+		{
+			MemoryContextSwitchTo(oldContext);
+			return;
+		}
+	}
+
 	/* We start from 1, since the 0th arg will be the transition value */
 	i = 1;
 	foreach(arg, wfuncstate->args)