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Properly acquire buffer lock for page-at-a-time hash vacuum.

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In a couple of places, _hash_kill_items was mistakenly called with
the buffer lock not held.  Repair.

Ashutosh Sharma, per a report from Andreas Seltenreich

Discussion: http://postgr.es/m/87o9wo8o0j.fsf@credativ.de
This commit is contained in:
Robert Haas 2017-04-03 22:24:17 -04:00
parent f578093526
commit 93cd7684ee
1 changed files with 18 additions and 2 deletions
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20
src/backend/access/hash/hash.c
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@ -476,9 +476,17 @@ hashrescan(IndexScanDesc scan, ScanKey scankey, int nscankeys,
HashScanOpaque so = (HashScanOpaque) scan->opaque;
Relation rel = scan->indexRelation;
/* Before leaving current page, deal with any killed items */
/*
* Before leaving current page, deal with any killed items.
* Also, ensure that we acquire lock on current page before
* calling _hash_kill_items.
*/
if (so->numKilled > 0)
{
LockBuffer(so->hashso_curbuf, BUFFER_LOCK_SHARE);
_hash_kill_items(scan);
LockBuffer(so->hashso_curbuf, BUFFER_LOCK_UNLOCK);
}
_hash_dropscanbuf(rel, so);
@ -507,9 +515,17 @@ hashendscan(IndexScanDesc scan)
HashScanOpaque so = (HashScanOpaque) scan->opaque;
Relation rel = scan->indexRelation;
/* Before leaving current page, deal with any killed items */
/*
* Before leaving current page, deal with any killed items.
* Also, ensure that we acquire lock on current page before
* calling _hash_kill_items.
*/
if (so->numKilled > 0)
{
LockBuffer(so->hashso_curbuf, BUFFER_LOCK_SHARE);
_hash_kill_items(scan);
LockBuffer(so->hashso_curbuf, BUFFER_LOCK_UNLOCK);
}
_hash_dropscanbuf(rel, so);