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Now that we've rearranged relation open to get a lock before touching

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the rel, it's easy to get rid of the narrow race-condition window that
used to exist in VACUUM and CLUSTER.  Did some minor code-beautification
work in the same area, too.
This commit is contained in:
Tom Lane
2006-08-18 16:09:13 +00:00
parent e91600d1c2
commit 7aa772f03e
8 changed files with 153 additions and 91 deletions
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16
src/backend/commands/analyze.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.96 2006/07/14 14:52:18 momjian Exp $
* $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.97 2006/08/18 16:09:08 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -129,20 +129,16 @@ analyze_rel(Oid relid, VacuumStmt *vacstmt)
CHECK_FOR_INTERRUPTS();
/*
* Race condition -- if the pg_class tuple has gone away since the last
* time we saw it, we don't need to process it.
* Open the relation, getting only a read lock on it. If the rel has
* been dropped since we last saw it, we don't need to process it.
*/
if (!SearchSysCacheExists(RELOID,
ObjectIdGetDatum(relid),
0, 0, 0))
onerel = try_relation_open(relid, AccessShareLock);
if (!onerel)
return;
/*
* Open the class, getting only a read lock on it, and check permissions.
* Permissions check should match vacuum's check!
* Check permissions --- this should match vacuum's check!
*/
onerel = relation_open(relid, AccessShareLock);
if (!(pg_class_ownercheck(RelationGetRelid(onerel), GetUserId()) ||
(pg_database_ownercheck(MyDatabaseId, GetUserId()) && !onerel->rd_rel->relisshared)))
{