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During heap rebuild, lock any TOAST index until end of transaction. 

swap_relation_files() calls toast_get_valid_index() to find and lock
this index, just before swapping with the rebuilt TOAST index.  The
latter function releases the lock before returning.  Potential for
mischief is low; a concurrent session can issue ALTER INDEX ... SET
(fillfactor = ...), which is not alarming.  Nonetheless, changing
pg_class.relfilenode without a lock is unconventional.  Back-patch to
9.5 (all supported versions), because another fix needs this.

Discussion: https://postgr.es/m/20191226001521.GA1772687@rfd.leadboat.com
This commit is contained in:
Noah Misch 2020-03-21 09:38:26 -07:00
parent 96dffcdd5b
commit 978da2a955
2 changed files with 3 additions and 3 deletions
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4
src/backend/access/heap/tuptoaster.c
View File

@ -1377,8 +1377,8 @@ toast_get_valid_index(Oid toastoid, LOCKMODE lock)
validIndexOid = RelationGetRelid(toastidxs[validIndex]);
/* Close the toast relation and all its indexes */
toast_close_indexes(toastidxs, num_indexes, lock);
heap_close(toastrel, lock);
toast_close_indexes(toastidxs, num_indexes, NoLock);
heap_close(toastrel, NoLock);
return validIndexOid;
}

2
src/backend/commands/cluster.c
View File

@ -1614,7 +1614,7 @@ finish_heap_swap(Oid OIDOldHeap, Oid OIDNewHeap,
/* Get the associated valid index to be renamed */
toastidx = toast_get_valid_index(newrel->rd_rel->reltoastrelid,
AccessShareLock);
NoLock);
/* rename the toast table ... */
snprintf(NewToastName, NAMEDATALEN, "pg_toast_%u",