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Improve subscription locking

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This avoids "tuple concurrently updated" errors when a ALTER or DROP
SUBSCRIPTION writes to pg_subscription_rel at the same time as a worker.

Author: Petr Jelinek <petr.jelinek@2ndquadrant.com>
This commit is contained in:
Peter Eisentraut 2017-07-03 22:47:06 -04:00
parent 42794d6749
commit cb9079cd51
2 changed files with 7 additions and 0 deletions
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4
src/backend/catalog/pg_subscription.c
View File

@ -28,6 +28,8 @@
#include "nodes/makefuncs.h" #include "nodes/makefuncs.h"
#include "storage/lmgr.h"
#include "utils/array.h" #include "utils/array.h"
#include "utils/builtins.h" #include "utils/builtins.h"
#include "utils/fmgroids.h" #include "utils/fmgroids.h"
@ -246,6 +248,8 @@ SetSubscriptionRelState(Oid subid, Oid relid, char state,
bool nulls[Natts_pg_subscription_rel]; bool nulls[Natts_pg_subscription_rel];
Datum values[Natts_pg_subscription_rel]; Datum values[Natts_pg_subscription_rel];
LockSharedObject(SubscriptionRelationId, subid, 0, AccessShareLock);
rel = heap_open(SubscriptionRelRelationId, RowExclusiveLock); rel = heap_open(SubscriptionRelRelationId, RowExclusiveLock);
/* Try finding existing mapping. */ /* Try finding existing mapping. */

3
src/backend/commands/subscriptioncmds.c
View File

@ -644,6 +644,9 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
subid = HeapTupleGetOid(tup); subid = HeapTupleGetOid(tup);
sub = GetSubscription(subid, false); sub = GetSubscription(subid, false);
/* Lock the subscription so nobody else can do anything with it. */
LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
/* Form a new tuple. */ /* Form a new tuple. */
memset(values, 0, sizeof(values)); memset(values, 0, sizeof(values));
memset(nulls, false, sizeof(nulls)); memset(nulls, false, sizeof(nulls));