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authorThomas Munro <tmunro@postgresql.org>2019-06-28 11:11:26 +1200
committerThomas Munro <tmunro@postgresql.org>2019-06-28 17:15:39 +1200
commit6827e46cdf351678f71577efd4736f5d443b6e01 (patch)
tree03c5bf6198e2b16e7da44d81f70e00c356bf4621
parent803cdf22a2d395653496702af789ccae7c17e18c (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 8c32a74d39e..7d2d50691e8 100644
--- a/src/backend/executor/nodeIndexonlyscan.c
+++ b/src/backend/executor/nodeIndexonlyscan.c
@@ -236,11 +236,8 @@ 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,