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authorThomas Munro2019-06-27 23:11:26 +0000
committerThomas Munro2019-06-28 05:17:23 +0000
commit0908c5ecf0833b020b0d95183804ebc22bb6ea6c (patch)
tree42f75ee37226ad958738673b125301d716adb723
parent30e1b395c9cfee997c9f44cfb27c3c6ec06b5a25 (diff)
Fix misleading comment in nodeIndexonlyscan.c.
The stated reason for acquiring predicate locks on heap pages hasn't existed since commit c01262a8, so fix the comment. Perhaps in a later release we'll also be able to change the code to use tuple locks. Back-patch all the way. Reviewed-by: Ashwin Agrawal Discussion: https://postgr.es/m/CAEepm%3D2GK3FVdnt5V3d%2Bh9njWipCv_fNL%3DwjxyUhzsF%3D0PcbNg%40mail.gmail.com
-rw-r--r--src/backend/executor/nodeIndexonlyscan.c7
1 files changed, 2 insertions, 5 deletions
diff --git a/src/backend/executor/nodeIndexonlyscan.c b/src/backend/executor/nodeIndexonlyscan.c
index 4f6f91c8dba..24a718d5366 100644
--- a/src/backend/executor/nodeIndexonlyscan.c
+++ b/src/backend/executor/nodeIndexonlyscan.c
@@ -179,11 +179,8 @@ IndexOnlyNext(IndexOnlyScanState *node)
errmsg("lossy distance functions are not supported in index-only scans")));
/*
- * Predicate locks for index-only scans must be acquired at the page
- * level when the heap is not accessed, since tuple-level predicate
- * locks need the tuple's xmin value. If we had to visit the tuple
- * anyway, then we already have the tuple-level lock and can skip the
- * page lock.
+ * If we didn't access the heap, then we'll need to take a predicate
+ * lock explicitly, as if we had. For now we do that at page level.
*/
if (tuple == NULL)
PredicateLockPage(scandesc->heapRelation,