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Fix up rickety handling of relation-truncation interlocks.

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Move rd_targblock, rd_fsm_nblocks, and rd_vm_nblocks from relcache to the smgr
relation entries, so that they will get reset to InvalidBlockNumber whenever
an smgr-level flush happens.  Because we now send smgr invalidation messages
immediately (not at end of transaction) when a relation truncation occurs,
this ensures that other backends will reset their values before they next
access the relation.  We no longer need the unreliable assumption that a
VACUUM that's doing a truncation will hold its AccessExclusive lock until
commit --- in fact, we can intentionally release that lock as soon as we've
completed the truncation.  This patch therefore reverts (most of) Alvaro's
patch of 2009-11-10, as well as my marginal hacking on it yesterday.  We can
also get rid of assorted no-longer-needed relcache flushes, which are far more
expensive than an smgr flush because they kill a lot more state.

In passing this patch fixes smgr_redo's failure to perform visibility-map
truncation, and cleans up some rather dubious assumptions in freespace.c and
visibilitymap.c about when rd_fsm_nblocks and rd_vm_nblocks can be out of
date.
This commit is contained in:
Tom Lane
2010-02-09 21:43:30 +00:00
parent 79647eed86
commit cbe9d6beb4
15 changed files with 210 additions and 219 deletions
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5
src/backend/access/transam/xlogutils.c
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@ -11,7 +11,7 @@
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/backend/access/transam/xlogutils.c,v 1.69 2010/01/02 16:57:35 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/transam/xlogutils.c,v 1.70 2010/02/09 21:43:29 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -393,9 +393,6 @@ CreateFakeRelcacheEntry(RelFileNode rnode)
rel->rd_lockInfo.lockRelId.dbId = rnode.dbNode;
rel->rd_lockInfo.lockRelId.relId = rnode.relNode;
rel->rd_targblock = InvalidBlockNumber;
rel->rd_fsm_nblocks = InvalidBlockNumber;
rel->rd_vm_nblocks = InvalidBlockNumber;
rel->rd_smgr = NULL;
return rel;