Reuse abbreviated keys in ordered [set] aggregates.

When processing ordered aggregates following a sort that could make use
of the abbreviated key optimization, only call the equality operator to
compare successive pairs of tuples when their abbreviated keys were not
equal.

Peter Geoghegan, reviewd by Andreas Karlsson and by me.

2 files changed, 14 insertions, 4 deletions

diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index b5aac67489d..03aa20f61e0 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -575,7 +575,8 @@ fetch_input_tuple(AggState *aggstate)
 
 	if (aggstate->sort_in)
 	{
-		if (!tuplesort_gettupleslot(aggstate->sort_in, true, aggstate->sort_slot))
+		if (!tuplesort_gettupleslot(aggstate->sort_in, true, aggstate->sort_slot,
+									NULL))
 			return NULL;
 		slot = aggstate->sort_slot;
 	}
@@ -1076,6 +1077,8 @@ process_ordered_aggregate_single(AggState *aggstate,
 	MemoryContext workcontext = aggstate->tmpcontext->ecxt_per_tuple_memory;
 	MemoryContext oldContext;
 	bool		isDistinct = (pertrans->numDistinctCols > 0);
+	Datum		newAbbrevVal = (Datum) 0;
+	Datum		oldAbbrevVal = (Datum) 0;
 	FunctionCallInfo fcinfo = &pertrans->transfn_fcinfo;
 	Datum	   *newVal;
 	bool	   *isNull;
@@ -1095,7 +1098,7 @@ process_ordered_aggregate_single(AggState *aggstate,
 	 */
 
 	while (tuplesort_getdatum(pertrans->sortstates[aggstate->current_set],
-							  true, newVal, isNull))
+							  true, newVal, isNull, &newAbbrevVal))
 	{
 		/*
 		 * Clear and select the working context for evaluation of the equality
@@ -1113,6 +1116,7 @@ process_ordered_aggregate_single(AggState *aggstate,
 			haveOldVal &&
 			((oldIsNull && *isNull) ||
 			 (!oldIsNull && !*isNull &&
+			  oldAbbrevVal == newAbbrevVal &&
 			  DatumGetBool(FunctionCall2(&pertrans->equalfns[0],
 										 oldVal, *newVal)))))
 		{
@@ -1128,6 +1132,7 @@ process_ordered_aggregate_single(AggState *aggstate,
 				pfree(DatumGetPointer(oldVal));
 			/* and remember the new one for subsequent equality checks */
 			oldVal = *newVal;
+			oldAbbrevVal = newAbbrevVal;
 			oldIsNull = *isNull;
 			haveOldVal = true;
 		}
@@ -1165,6 +1170,8 @@ process_ordered_aggregate_multi(AggState *aggstate,
 	TupleTableSlot *slot2 = pertrans->uniqslot;
 	int			numTransInputs = pertrans->numTransInputs;
 	int			numDistinctCols = pertrans->numDistinctCols;
+	Datum		newAbbrevVal = (Datum) 0;
+	Datum		oldAbbrevVal = (Datum) 0;
 	bool		haveOldValue = false;
 	int			i;
 
@@ -1175,7 +1182,7 @@ process_ordered_aggregate_multi(AggState *aggstate,
 		ExecClearTuple(slot2);
 
 	while (tuplesort_gettupleslot(pertrans->sortstates[aggstate->current_set],
-								  true, slot1))
+								  true, slot1, &newAbbrevVal))
 	{
 		/*
 		 * Extract the first numTransInputs columns as datums to pass to the
@@ -1186,6 +1193,7 @@ process_ordered_aggregate_multi(AggState *aggstate,
 
 		if (numDistinctCols == 0 ||
 			!haveOldValue ||
+			newAbbrevVal != oldAbbrevVal ||
 			!execTuplesMatch(slot1, slot2,
 							 numDistinctCols,
 							 pertrans->sortColIdx,
@@ -1209,6 +1217,8 @@ process_ordered_aggregate_multi(AggState *aggstate,
 
 				slot2 = slot1;
 				slot1 = tmpslot;
+				/* avoid execTuplesMatch() calls by reusing abbreviated keys */
+				oldAbbrevVal = newAbbrevVal;
 				haveOldValue = true;
 			}
 		}
diff --git a/src/backend/executor/nodeSort.c b/src/backend/executor/nodeSort.c
index 102dbdfc124..a34dcc51358 100644
--- a/src/backend/executor/nodeSort.c
+++ b/src/backend/executor/nodeSort.c
@@ -137,7 +137,7 @@ ExecSort(SortState *node)
 	slot = node->ss.ps.ps_ResultTupleSlot;
 	(void) tuplesort_gettupleslot(tuplesortstate,
 								  ScanDirectionIsForward(dir),
-								  slot);
+								  slot, NULL);
 	return slot;
 }