database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-05 07:21:24 +03:00
Code Activity

Fix up rickety handling of relation-truncation interlocks.

Browse Source 
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visibilitymap.c about when rd_fsm_nblocks and rd_vm_nblocks can be out of
date.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
Download Patch File Download Diff File Expand all files Collapse all files

39
src/backend/utils/cache/relcache.c vendored
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.304 2010/02/08 05:53:55 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.305 2010/02/09 21:43:30 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -328,13 +328,6 @@ AllocateRelationDesc(Form_pg_class relp)
*/
relation = (Relation) palloc0(sizeof(RelationData));
/*
* clear fields of reldesc that should initialize to something non-zero
*/
relation->rd_targblock = InvalidBlockNumber;
relation->rd_fsm_nblocks = InvalidBlockNumber;
relation->rd_vm_nblocks = InvalidBlockNumber;
/* make sure relation is marked as having no open file yet */
relation->rd_smgr = NULL;
@ -1413,9 +1406,6 @@ formrdesc(const char *relationName, Oid relationReltype,
* allocate new relation desc, clear all fields of reldesc
*/
relation = (Relation) palloc0(sizeof(RelationData));
relation->rd_targblock = InvalidBlockNumber;
relation->rd_fsm_nblocks = InvalidBlockNumber;
relation->rd_vm_nblocks = InvalidBlockNumber;
/* make sure relation is marked as having no open file yet */
relation->rd_smgr = NULL;
@ -1714,14 +1704,7 @@ RelationReloadIndexInfo(Relation relation)
/* Should be closed at smgr level */
Assert(relation->rd_smgr == NULL);
/*
* Must reset targblock, fsm_nblocks and vm_nblocks in case rel was
* truncated
*/
relation->rd_targblock = InvalidBlockNumber;
relation->rd_fsm_nblocks = InvalidBlockNumber;
relation->rd_vm_nblocks = InvalidBlockNumber;
/* Must free any AM cached data, too */
/* Must free any AM cached data upon relcache flush */
if (relation->rd_amcache)
pfree(relation->rd_amcache);
relation->rd_amcache = NULL;
@ -1867,11 +1850,8 @@ RelationClearRelation(Relation relation, bool rebuild)
/*
* Never, never ever blow away a nailed-in system relation, because we'd
* be unable to recover. However, we must reset rd_targblock, in case we
* got called because of a relation cache flush that was triggered by
* VACUUM. Likewise reset the fsm and vm size info. Also, redo
* RelationInitPhysicalAddr in case it is a mapped relation whose mapping
* changed.
* be unable to recover. However, we must redo RelationInitPhysicalAddr
* in case it is a mapped relation whose mapping changed.
*
* If it's a nailed index, then we need to re-read the pg_class row to see
* if its relfilenode changed. We can't necessarily do that here, because
@ -1882,10 +1862,6 @@ RelationClearRelation(Relation relation, bool rebuild)
*/
if (relation->rd_isnailed)
{
relation->rd_targblock = InvalidBlockNumber;
relation->rd_fsm_nblocks = InvalidBlockNumber;
relation->rd_vm_nblocks = InvalidBlockNumber;
/* We must recalculate physical address in case it changed */
RelationInitPhysicalAddr(relation);
if (relation->rd_rel->relkind == RELKIND_INDEX)
@ -2502,10 +2478,6 @@ RelationBuildLocalRelation(const char *relname,
*/
rel = (Relation) palloc0(sizeof(RelationData));
rel->rd_targblock = InvalidBlockNumber;
rel->rd_fsm_nblocks = InvalidBlockNumber;
rel->rd_vm_nblocks = InvalidBlockNumber;
/* make sure relation is marked as having no open file yet */
rel->rd_smgr = NULL;
@ -4169,9 +4141,6 @@ load_relcache_init_file(bool shared)
* Reset transient-state fields in the relcache entry
*/
rel->rd_smgr = NULL;
rel->rd_targblock = InvalidBlockNumber;
rel->rd_fsm_nblocks = InvalidBlockNumber;
rel->rd_vm_nblocks = InvalidBlockNumber;
if (rel->rd_isnailed)
rel->rd_refcnt = 1;
else