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authorThomas Munro2019-06-27 23:11:26 +0000
committerThomas Munro2019-06-28 05:13:08 +0000
commit74b7cc8c02137f059703972aa14445b1e073f005 (patch)
tree6376dddfc3b1f957d112c928b9db1c25192d0ec9
parent69fd82fedd746b82427097883daf2921dd77584e (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 8a4d795d1a9..f0f8fa210ba 100644
--- a/src/backend/executor/nodeIndexonlyscan.c
+++ b/src/backend/executor/nodeIndexonlyscan.c
@@ -242,11 +242,8 @@ 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_from_heap)
PredicateLockPage(scandesc->heapRelation,