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Disallow CREATE/DROP SUBSCRIPTION in transaction block

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Disallow CREATE SUBSCRIPTION and DROP SUBSCRIPTION in a transaction
block when the replication slot is to be created or dropped, since that
cannot be rolled back.

based on patch by Masahiko Sawada <sawada.mshk@gmail.com>
This commit is contained in:
Peter Eisentraut 2017-03-03 23:25:34 -05:00
parent 347302730d
commit 272adf4f9c
7 changed files with 66 additions and 15 deletions
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5
doc/src/sgml/ref/create_subscription.sgml
View File

@ -51,6 +51,11 @@ CREATE SUBSCRIPTION <replaceable class="PARAMETER">subscription_name</replaceabl
subscription at the commit of the transaction where this command is run.
</para>
<para>
<command>CREATE SUBSCRIPTION</command> cannot be executed inside a
transaction block when <literal>CREATE SLOT</literal> is specified.
</para>
<para>
Additional info about subscriptions and logical replication as a whole
can is available at <xref linkend="logical-replication-subscription"> and

4
doc/src/sgml/ref/drop_subscription.sgml
View File

@ -38,8 +38,8 @@ DROP SUBSCRIPTION [ IF EXISTS ] <replaceable class="parameter">name</replaceable
</para>
<para>
The replication worker associated with the subscription will not stop until
after the transaction that issued this command has committed.
<command>DROP SUBSCRIPTION</command> cannot be executed inside a
transaction block when <literal>DROP SLOT</literal> is specified.
</para>
</refsect1>

38
src/backend/commands/subscriptioncmds.c
View File

@ -18,6 +18,7 @@
#include "access/heapam.h"
#include "access/htup_details.h"
#include "access/xact.h"
#include "catalog/indexing.h"
#include "catalog/objectaccess.h"
@ -204,7 +205,7 @@ publicationListToArray(List *publist)
* Create new subscription.
*/
ObjectAddress
CreateSubscription(CreateSubscriptionStmt *stmt)
CreateSubscription(CreateSubscriptionStmt *stmt, bool isTopLevel)
{
Relation rel;
ObjectAddress myself;
@ -221,6 +222,23 @@ CreateSubscription(CreateSubscriptionStmt *stmt)
bool create_slot;
List *publications;
/*
* Parse and check options.
* Connection and publication should not be specified here.
*/
parse_subscription_options(stmt->options, NULL, NULL,
&enabled_given, &enabled,
&create_slot, &slotname);
/*
* Since creating a replication slot is not transactional, rolling back
* the transaction leaves the created replication slot. So we cannot run
* CREATE SUBSCRIPTION inside a transaction block if creating a
* replication slot.
*/
if (create_slot)
PreventTransactionChain(isTopLevel, "CREATE SUBSCRIPTION ... CREATE SLOT");
if (!superuser())
ereport(ERROR,
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
@ -239,13 +257,6 @@ CreateSubscription(CreateSubscriptionStmt *stmt)
stmt->subname)));
}
/*
* Parse and check options.
* Connection and publication should not be specified here.
*/
parse_subscription_options(stmt->options, NULL, NULL,
&enabled_given, &enabled,
&create_slot, &slotname);
if (slotname == NULL)
slotname = stmt->subname;
@ -424,7 +435,7 @@ AlterSubscription(AlterSubscriptionStmt *stmt)
* Drop a subscription
*/
void
DropSubscription(DropSubscriptionStmt *stmt)
DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel)
{
Relation rel;
ObjectAddress myself;
@ -441,6 +452,15 @@ DropSubscription(DropSubscriptionStmt *stmt)
WalReceiverConn *wrconn = NULL;
StringInfoData cmd;
/*
* Since dropping a replication slot is not transactional, the replication
* slot stays dropped even if the transaction rolls back. So we cannot
* run DROP SUBSCRIPTION inside a transaction block if dropping the
* replication slot.
*/
if (stmt->drop_slot)
PreventTransactionChain(isTopLevel, "DROP SUBSCRIPTION ... DROP SLOT");
rel = heap_open(SubscriptionRelationId, RowExclusiveLock);
tup = SearchSysCache2(SUBSCRIPTIONNAME, MyDatabaseId,

5
src/backend/tcop/utility.c
View File

@ -1609,7 +1609,8 @@ ProcessUtilitySlow(ParseState *pstate,
break;
case T_CreateSubscriptionStmt:
address = CreateSubscription((CreateSubscriptionStmt *) parsetree);
address = CreateSubscription((CreateSubscriptionStmt *) parsetree,
isTopLevel);
break;
case T_AlterSubscriptionStmt:
@ -1617,7 +1618,7 @@ ProcessUtilitySlow(ParseState *pstate,
break;
case T_DropSubscriptionStmt:
DropSubscription((DropSubscriptionStmt *) parsetree);
DropSubscription((DropSubscriptionStmt *) parsetree, isTopLevel);
/* no commands stashed for DROP */
commandCollected = true;
break;

5
src/include/commands/subscriptioncmds.h
View File

@ -18,9 +18,10 @@
#include "catalog/objectaddress.h"
#include "nodes/parsenodes.h"
extern ObjectAddress CreateSubscription(CreateSubscriptionStmt *stmt);
extern ObjectAddress CreateSubscription(CreateSubscriptionStmt *stmt,
bool isTopLevel);
extern ObjectAddress AlterSubscription(AlterSubscriptionStmt *stmt);
extern void DropSubscription(DropSubscriptionStmt *stmt);
extern void DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel);
extern ObjectAddress AlterSubscriptionOwner(const char *name, Oid newOwnerId);
extern void AlterSubscriptionOwner_oid(Oid subid, Oid newOwnerId);

12
src/test/regress/expected/subscription.out
View File

@ -14,6 +14,11 @@ ERROR: syntax error at or near "PUBLICATION"
LINE 1: CREATE SUBSCRIPTION testsub PUBLICATION foo;
^
set client_min_messages to error;
-- fail - cannot do CREATE SUBSCRIPTION CREATE SLOT inside transaction block
BEGIN;
CREATE SUBSCRIPTION testsub CONNECTION 'testconn' PUBLICATION testpub WITH (CREATE SLOT);
ERROR: CREATE SUBSCRIPTION ... CREATE SLOT cannot run inside a transaction block
COMMIT;
CREATE SUBSCRIPTION testsub CONNECTION 'testconn' PUBLICATION testpub;
ERROR: invalid connection string syntax: missing "=" after "testconn" in connection info string
@ -69,6 +74,13 @@ ALTER SUBSCRIPTION testsub RENAME TO testsub_foo;
testsub_foo | regress_subscription_user | f | {testpub,testpub1}
(1 row)
-- fail - cannot do DROP SUBSCRIPTION DROP SLOT inside transaction block
BEGIN;
DROP SUBSCRIPTION testsub DROP SLOT;
ERROR: DROP SUBSCRIPTION ... DROP SLOT cannot run inside a transaction block
COMMIT;
BEGIN;
DROP SUBSCRIPTION testsub_foo NODROP SLOT;
COMMIT;
RESET SESSION AUTHORIZATION;
DROP ROLE regress_subscription_user;

12
src/test/regress/sql/subscription.sql
View File

@ -12,6 +12,11 @@ CREATE SUBSCRIPTION testsub CONNECTION 'foo';
CREATE SUBSCRIPTION testsub PUBLICATION foo;
set client_min_messages to error;
-- fail - cannot do CREATE SUBSCRIPTION CREATE SLOT inside transaction block
BEGIN;
CREATE SUBSCRIPTION testsub CONNECTION 'testconn' PUBLICATION testpub WITH (CREATE SLOT);
COMMIT;
CREATE SUBSCRIPTION testsub CONNECTION 'testconn' PUBLICATION testpub;
CREATE SUBSCRIPTION testsub CONNECTION 'dbname=doesnotexist' PUBLICATION testpub WITH (DISABLED, NOCREATE SLOT);
reset client_min_messages;
@ -42,7 +47,14 @@ ALTER SUBSCRIPTION testsub RENAME TO testsub_foo;
\dRs
-- fail - cannot do DROP SUBSCRIPTION DROP SLOT inside transaction block
BEGIN;
DROP SUBSCRIPTION testsub DROP SLOT;
COMMIT;
BEGIN;
DROP SUBSCRIPTION testsub_foo NODROP SLOT;
COMMIT;
RESET SESSION AUTHORIZATION;
DROP ROLE regress_subscription_user;