Avoid extra lookups with nbtree array inequalities.

petergeoghegan · petergeoghegan · commit 473411fc5115 · 2024-04-07T14:15:54.000-04:00
nbtree index scans with SAOP inequalities (but no SAOP equalities) performed extra ORDER proc lookups for any remaining equality strategy scan keys. This could waste cycles, and caused assertion failures. Keeping around a separate ORDER proc is only necessary for a scan's non-array/non-SAOP equality scan keys when the scan has at least one other SAOP equality strategy key (a SAOP inequality shouldn't count). To fix, replace _bt_preprocess_array_keys_final's assertion with a test that makes the function return early when the scan has no SAOP equality scan keys. Oversight in commit 1b134ca, which enhanced nbtree ScalarArrayOp execution. Reported-By: Alexander Lakhin <exclusion@gmail.com> Discussion: https://postgr.es/m/0539d3d3-a402-0a49-ed5e-26429dffc4bd@gmail.com
diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c
@@ -557,7 +557,13 @@ _bt_preprocess_array_keys_final(IndexScanDesc scan, int *keyDataMap)
 	int			last_equal_output_ikey PG_USED_FOR_ASSERTS_ONLY = -1;
 
 	Assert(so->qual_ok);
-	Assert(so->numArrayKeys);
+
+	/*
+	 * Nothing for us to do when _bt_preprocess_array_keys only had to deal
+	 * with array inequalities
+	 */
+	if (so->numArrayKeys == 0)
+		return;
 
 	for (int output_ikey = 0; output_ikey < so->numberOfKeys; output_ikey++)
 	{
