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Predicate locking in hash indexes.

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Hash index searches acquire predicate locks on the primary
page of a bucket. It acquires a lock on both the old and new buckets
for scans that happen concurrently with page splits. During a bucket
split, a predicate lock is copied from the primary page of an old
bucket to the primary page of a new bucket.

Author: Shubham Barai, Amit Kapila
Reviewed by: Amit Kapila, Alexander Korotkov, Thomas Munro
Discussion: https://www.postgresql.org/message-id/flat/CALxAEPvNsM2GTiXdRgaaZ1Pjd1bs+sxfFsf7Ytr+iq+5JJoYXA@mail.gmail.com
This commit is contained in:
Teodor Sigaev
2018-04-07 16:59:14 +03:00
parent 971d7ddbe1
commit b508a56f2f
8 changed files with 802 additions and 1 deletions
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src/backend/storage/lmgr/README-SSI
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@@ -389,6 +389,13 @@ relation is required. Fast update postpones the insertion of tuples into index
structure by temporarily storing them into pending list. That makes us unable
to detect r-w conflicts using page-level locks.
* Hash index searches acquire predicate locks on the primary
page of a bucket. It acquires a lock on both the old and new buckets
for scans that happen concurrently with page splits. During a bucket
split, a predicate lock is copied from the primary page of an old
bucket to the primary page of a new bucket.
* The effects of page splits, overflows, consolidations, and
removals must be carefully reviewed to ensure that predicate locks
aren't "lost" during those operations, or kept with pages which could