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authorThomas Munro <tmunro@postgresql.org>2019-06-28 11:11:26 +1200
committerThomas Munro <tmunro@postgresql.org>2019-06-28 17:16:44 +1200
commit69da8c1e69efd3a5b1b0f1d9bd8b7b79a696fbc8 (patch)
treea854251e835eddda5918682e263d1aceea13ffe4 /src/backend/executor
parent0161e522cbb536d8978ca8e5b5341b16805cc6b4 (diff)
downloadpostgresql-69da8c1e69efd3a5b1b0f1d9bd8b7b79a696fbc8.tar.gz
postgresql-69da8c1e69efd3a5b1b0f1d9bd8b7b79a696fbc8.zip
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
Diffstat (limited to 'src/backend/executor')
-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 f452e0fd5ff..338429bd589 100644
--- a/src/backend/executor/nodeIndexonlyscan.c
+++ b/src/backend/executor/nodeIndexonlyscan.c
@@ -237,11 +237,8 @@ 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,