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Put a critical section around update of hash index metapage. Per

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discussion with Qingqing Zhou.
This commit is contained in:
Tom Lane 2005-06-09 18:23:50 +00:00
parent 65d27324c3
commit 82358ca936
1 changed files with 12 additions and 1 deletions
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13
src/backend/access/hash/hashpage.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/hash/hashpage.c,v 1.49 2005/05/11 01:26:01 neilc Exp $
* $PostgreSQL: pgsql/src/backend/access/hash/hashpage.c,v 1.50 2005/06/09 18:23:50 tgl Exp $
*
* NOTES
* Postgres hash pages look like ordinary relation pages. The opaque
@ -421,7 +421,15 @@ _hash_expandtable(Relation rel, Buffer metabuf)
/*
* Okay to proceed with split. Update the metapage bucket mapping
* info.
*
* Since we are scribbling on the metapage data right in the shared
* buffer, any failure in this next little bit leaves us with a big
* problem: the metapage is effectively corrupt but could get written
* back to disk. We don't really expect any failure, but just to be
* sure, establish a critical section.
*/
START_CRIT_SECTION();
metap->hashm_maxbucket = new_bucket;
if (new_bucket > metap->hashm_highmask)
@ -456,6 +464,9 @@ _hash_expandtable(Relation rel, Buffer metabuf)
if (!_hash_try_getlock(rel, start_nblkno, HASH_EXCLUSIVE))
elog(PANIC, "could not get lock on supposedly new bucket");
/* Done mucking with metapage */
END_CRIT_SECTION();
/*
* Copy bucket mapping info now; this saves re-accessing the meta page
* inside _hash_splitbucket's inner loop. Note that once we drop the