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Commit8bfd1a8

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Lock database while running drop database in Hot Standby to protect
against concurrent reconnection. Failure during testing showed issuewas possible, even though earlier analysis seemed to indicate itwould not be required. Use LockSharedObjectForSession() beforeResolveRecoveryConflictWithDatabase() and hold lock until end ofprocessing for that WAL record. Simple approach to avoid introducingfurther bugs at this stage of development on an improbable issue.
1 parent40b91b3 commit8bfd1a8

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‎src/backend/commands/dbcommands.c

Lines changed: 20 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -13,7 +13,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/commands/dbcommands.c,v 1.232 2010/01/14 11:08:00 sriggs Exp $
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* $PostgreSQL: pgsql/src/backend/commands/dbcommands.c,v 1.233 2010/01/16 14:16:31 sriggs Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -1944,7 +1944,15 @@ dbase_redo(XLogRecPtr lsn, XLogRecord *record)
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dst_path=GetDatabasePath(xlrec->db_id,xlrec->tablespace_id);
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if (InHotStandby)
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{
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/*
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* Lock database while we resolve conflicts to ensure that InitPostgres()
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* cannot fully re-execute concurrently. This avoids backends re-connecting
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* automatically to same database, which can happen in some cases.
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*/
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LockSharedObjectForSession(DatabaseRelationId,xlrec->db_id,0,AccessExclusiveLock);
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ResolveRecoveryConflictWithDatabase(xlrec->db_id);
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}
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/* Drop pages for this database that are in the shared buffer cache */
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DropDatabaseBuffers(xlrec->db_id);
@@ -1960,6 +1968,17 @@ dbase_redo(XLogRecPtr lsn, XLogRecord *record)
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ereport(WARNING,
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(errmsg("some useless files may be left behind in old database directory \"%s\"",
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dst_path)));
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if (InHotStandby)
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{
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/*
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* Release locks prior to commit. XXX There is a race condition here that may allow
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* backends to reconnect, but the window for this is small because the gap between
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* here and commit is mostly fairly small and it is unlikely that people will be
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* dropping databases that we are trying to connect to anyway.
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*/
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UnlockSharedObjectForSession(DatabaseRelationId,xlrec->db_id,0,AccessExclusiveLock);
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}
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}
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else
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elog(PANIC,"dbase_redo: unknown op code %u",info);

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