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authorPeter Eisentraut2017-07-04 02:47:06 +0000
committerPeter Eisentraut2017-07-04 02:47:06 +0000
commitcb9079cd51a2df677dc182aec72d88383b9c2a79 (patch)
treed4e940aec147b7b21b3a5db5f21ffa991b77ccc8
parent42794d6749f24636efbb198db17c30c63df10900 (diff)
Improve subscription locking
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 <[email protected]>
-rw-r--r--src/backend/catalog/pg_subscription.c4
-rw-r--r--src/backend/commands/subscriptioncmds.c3
2 files changed, 7 insertions, 0 deletions
diff --git a/src/backend/catalog/pg_subscription.c b/src/backend/catalog/pg_subscription.c
index c69c461b62..fb53d71cd6 100644
--- a/src/backend/catalog/pg_subscription.c
+++ b/src/backend/catalog/pg_subscription.c
@@ -28,6 +28,8 @@
#include "nodes/makefuncs.h"
+#include "storage/lmgr.h"
+
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
@@ -246,6 +248,8 @@ SetSubscriptionRelState(Oid subid, Oid relid, char state,
bool nulls[Natts_pg_subscription_rel];
Datum values[Natts_pg_subscription_rel];
+ LockSharedObject(SubscriptionRelationId, subid, 0, AccessShareLock);
+
rel = heap_open(SubscriptionRelRelationId, RowExclusiveLock);
/* Try finding existing mapping. */
diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c
index 9cbd36f646..6dc3f6ee00 100644
--- a/src/backend/commands/subscriptioncmds.c
+++ b/src/backend/commands/subscriptioncmds.c
@@ -644,6 +644,9 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
subid = HeapTupleGetOid(tup);
sub = GetSubscription(subid, false);
+ /* Lock the subscription so nobody else can do anything with it. */
+ LockSharedObject(SubscriptionRelationId, subid, 0, AccessExclusiveLock);
+
/* Form a new tuple. */
memset(values, 0, sizeof(values));
memset(nulls, false, sizeof(nulls));