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Force pg_database updates out to disk immediately after ALTER DATABASE;

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this is to avoid scenarios where incoming backends find no live copies
of a database's row because the only live copy is in an as-yet-unwritten
shared buffer, which they can't see.  Also, use FlushRelationBuffers()
for forcing out pg_database, instead of the much more expensive BufferSync().
There's no need to write out pages belonging to other relations.
This commit is contained in:
Tom Lane 2004-11-18 01:14:26 +00:00
parent c36496a101
commit b2a2f4cef7
1 changed files with 48 additions and 20 deletions
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68
src/backend/commands/dbcommands.c
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@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/dbcommands.c,v 1.146 2004/10/28 00:39:58 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/dbcommands.c,v 1.147 2004/11/18 01:14:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -330,7 +330,7 @@ createdb(const CreatedbStmt *stmt)
/*
* Force dirty buffers out to disk, to ensure source database is
* up-to-date for the copy. (We really only need to flush buffers for
* the source database...)
* the source database, but bufmgr.c provides no API for that.)
*/
BufferSync(-1, -1);
@ -497,15 +497,15 @@ createdb(const CreatedbStmt *stmt)
/* Update indexes */
CatalogUpdateIndexes(pg_database_rel, tuple);
/* Close pg_database, but keep lock till commit */
heap_close(pg_database_rel, NoLock);
/*
* Force dirty buffers out to disk, so that newly-connecting backends
* will see the new database in pg_database right away. (They'll see
* an uncommitted tuple, but they don't care; see GetRawDatabaseInfo.)
*/
BufferSync(-1, -1);
FlushRelationBuffers(pg_database_rel, MaxBlockNumber);
/* Close pg_database, but keep exclusive lock till commit */
heap_close(pg_database_rel, NoLock);
}
@ -607,12 +607,6 @@ dropdb(const char *dbname)
*/
DeleteComments(db_id, RelationGetRelid(pgdbrel), 0);
/*
* Close pg_database, but keep exclusive lock till commit to ensure
* that any new backend scanning pg_database will see the tuple dead.
*/
heap_close(pgdbrel, NoLock);
/*
* Drop pages for this database that are in the shared buffer cache.
* This is important to ensure that no remaining backend tries to
@ -644,7 +638,10 @@ dropdb(const char *dbname)
* (They'll see an uncommitted deletion, but they don't care; see
* GetRawDatabaseInfo.)
*/
BufferSync(-1, -1);
FlushRelationBuffers(pgdbrel, MaxBlockNumber);
/* Close pg_database, but keep exclusive lock till commit */
heap_close(pgdbrel, NoLock);
}
@ -733,7 +730,6 @@ RenameDatabase(const char *oldname, const char *newname)
CatalogUpdateIndexes(rel, newtup);
systable_endscan(scan);
heap_close(rel, NoLock);
/*
* Force dirty buffers out to disk, so that newly-connecting backends
@ -741,7 +737,10 @@ RenameDatabase(const char *oldname, const char *newname)
* see an uncommitted tuple, but they don't care; see
* GetRawDatabaseInfo.)
*/
BufferSync(-1, -1);
FlushRelationBuffers(rel, MaxBlockNumber);
/* Close pg_database, but keep exclusive lock till commit */
heap_close(rel, NoLock);
}
@ -763,7 +762,10 @@ AlterDatabaseSet(AlterDatabaseSetStmt *stmt)
valuestr = flatten_set_variable_args(stmt->variable, stmt->value);
rel = heap_openr(DatabaseRelationName, RowExclusiveLock);
/*
* We need AccessExclusiveLock so we can safely do FlushRelationBuffers.
*/
rel = heap_openr(DatabaseRelationName, AccessExclusiveLock);
ScanKeyInit(&scankey,
Anum_pg_database_datname,
BTEqualStrategyNumber, F_NAMEEQ,
@ -821,6 +823,16 @@ AlterDatabaseSet(AlterDatabaseSetStmt *stmt)
CatalogUpdateIndexes(rel, newtuple);
systable_endscan(scan);
/*
* Force dirty buffers out to disk, so that newly-connecting backends
* will see the altered row in pg_database right away. (They'll
* see an uncommitted tuple, but they don't care; see
* GetRawDatabaseInfo.)
*/
FlushRelationBuffers(rel, MaxBlockNumber);
/* Close pg_database, but keep exclusive lock till commit */
heap_close(rel, NoLock);
}
@ -837,7 +849,10 @@ AlterDatabaseOwner(const char *dbname, AclId newOwnerSysId)
SysScanDesc scan;
Form_pg_database datForm;
rel = heap_openr(DatabaseRelationName, RowExclusiveLock);
/*
* We need AccessExclusiveLock so we can safely do FlushRelationBuffers.
*/
rel = heap_openr(DatabaseRelationName, AccessExclusiveLock);
ScanKeyInit(&scankey,
Anum_pg_database_datname,
BTEqualStrategyNumber, F_NAMEEQ,
@ -901,9 +916,22 @@ AlterDatabaseOwner(const char *dbname, AclId newOwnerSysId)
CatalogUpdateIndexes(rel, newtuple);
heap_freetuple(newtuple);
}
systable_endscan(scan);
/* must release buffer pins before FlushRelationBuffers */
systable_endscan(scan);
/*
* Force dirty buffers out to disk, so that newly-connecting backends
* will see the altered row in pg_database right away. (They'll
* see an uncommitted tuple, but they don't care; see
* GetRawDatabaseInfo.)
*/
FlushRelationBuffers(rel, MaxBlockNumber);
}
else
systable_endscan(scan);
/* Close pg_database, but keep exclusive lock till commit */
heap_close(rel, NoLock);
}
@ -1176,7 +1204,7 @@ dbase_redo(XLogRecPtr lsn, XLogRecord *record)
/*
* Force dirty buffers out to disk, to ensure source database is
* up-to-date for the copy. (We really only need to flush buffers for
* the source database...)
* the source database, but bufmgr.c provides no API for that.)
*/
BufferSync(-1, -1);