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Work around deadlock problems with VACUUM FULL/CLUSTER on system catalogs,

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as per my recent proposal.

First, teach IndexBuildHeapScan to not wait for INSERT_IN_PROGRESS or
DELETE_IN_PROGRESS tuples to commit unless the index build is checking
uniqueness/exclusion constraints.  If it isn't, there's no harm in just
indexing the in-doubt tuple.

Second, modify VACUUM FULL/CLUSTER to suppress reverifying
uniqueness/exclusion constraint properties while rebuilding indexes of
the target relation.  This is reasonable because these commands aren't
meant to deal with corrupted-data situations.  Constraint properties
will still be rechecked when an index is rebuilt by a REINDEX command.

This gets us out of the problem that new-style VACUUM FULL would often
wait for other transactions while holding exclusive lock on a system
catalog, leading to probable deadlock because those other transactions
need to look at the catalogs too.  Although the real ultimate cause of
the problem is a debatable choice to release locks early after modifying
system catalogs, changing that choice would require pretty serious
analysis and is not something to be undertaken lightly or on a tight
schedule.  The present patch fixes the problem in a fairly reasonable
way and should also improve the speed of VACUUM FULL/CLUSTER a little bit.
This commit is contained in:
Tom Lane
2010-02-07 22:40:33 +00:00
parent 1c05b0b4ea
commit 1ddc2703a9
5 changed files with 95 additions and 68 deletions
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3
src/backend/commands/cluster.c
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@ -11,7 +11,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/cluster.c,v 1.198 2010/02/07 20:48:10 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/cluster.c,v 1.199 2010/02/07 22:40:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -948,7 +948,6 @@ copy_heap_data(Oid OIDNewHeap, Oid OIDOldHeap, Oid OIDOldIndex,
*/
if (!is_system_catalog &&
!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple->t_data)))
elog(WARNING, "concurrent insert in progress within table \"%s\"",
RelationGetRelationName(OldHeap));
/* treat as live */