CREATE SUBSCRIPTION
CREATE SUBSCRIPTION
CREATE SUBSCRIPTION - define a new subscription
Synopsis
CREATE SUBSCRIPTIONsubscription_name
CONNECTION 'conninfo
' PUBLICATIONpublication_name
[, ...] [ WITH (subscription_parameter
[=value
] [, ... ] ) ]
Description
CREATE SUBSCRIPTION
adds a new subscription for the
current database. The subscription name must be distinct from the name of
any existing subscription in the database.
The subscription represents a replication connection to the publisher. As such this command does not only add definitions in the local catalogs but also creates a replication slot on the publisher.
A logical replication worker will be started to replicate data for the new subscription at the commit of the transaction where this command is run.
Additional information about subscriptions and logical replication as a whole is available at Section 31.2 and Chapter 31 .
Parameters
-
subscription_name
-
The name of the new subscription.
-
CONNECTION '
conninfo
' -
The connection string to the publisher. For details see Section 34.1.1 .
-
PUBLICATION
publication_name
-
Names of the publications on the publisher to subscribe to.
-
WITH (
subscription_parameter
[=value
] [, ... ] ) -
This clause specifies optional parameters for a subscription. The following parameters are supported:
-
copy_data
(boolean
) -
Specifies whether the existing data in the publications that are being subscribed to should be copied once the replication starts. The default is
true
. -
create_slot
(boolean
) -
Specifies whether the command should create the replication slot on the publisher. The default is
true
. -
enabled
(boolean
) -
Specifies whether the subscription should be actively replicating, or whether it should be just setup but not started yet. The default is
true
. -
slot_name
(string
) -
Name of the replication slot to use. The default behavior is to use the name of the subscription for the slot name.
When
slot_name
is set toNONE
, there will be no replication slot associated with the subscription. This can be used if the replication slot will be created later manually. Such subscriptions must also have bothenabled
andcreate_slot
set tofalse
. -
synchronous_commit
(enum
) -
The value of this parameter overrides the synchronous_commit setting. The default value is
off
.It is safe to use
off
for logical replication: If the subscriber loses transactions because of missing synchronization, the data will be resent from the publisher.A different setting might be appropriate when doing synchronous logical replication. The logical replication workers report the positions of writes and flushes to the publisher, and when using synchronous replication, the publisher will wait for the actual flush. This means that setting
synchronous_commit
for the subscriber tooff
when the subscription is used for synchronous replication might increase the latency forCOMMIT
on the publisher. In this scenario, it can be advantageous to setsynchronous_commit
tolocal
or higher. -
connect
(boolean
) -
Specifies whether the
CREATE SUBSCRIPTION
should connect to the publisher at all. Setting this tofalse
will change default values ofenabled
,create_slot
andcopy_data
tofalse
.It is not allowed to combine
connect
set tofalse
andenabled
,create_slot
, orcopy_data
set totrue
.Since no connection is made when this option is set to
false
, the tables are not subscribed, and so after you enable the subscription nothing will be replicated. It is required to runALTER SUBSCRIPTION ... REFRESH PUBLICATION
in order for tables to be subscribed.
-
Notes
See Section 31.7 for details on how to configure access control between the subscription and the publication instance.
When creating a replication slot (the default behavior),
CREATE
SUBSCRIPTION
cannot be executed inside a transaction block.
Creating a subscription that connects to the same database cluster (for
example, to replicate between databases in the same cluster or to replicate
within the same database) will only succeed if the replication slot is not
created as part of the same command. Otherwise, the
CREATE
SUBSCRIPTION
call will hang. To make this work, create the
replication slot separately (using the
function
pg_create_logical_replication_slot
with the
plugin name
pgoutput
) and create the subscription using
the parameter
create_slot = false
. This is an
implementation restriction that might be lifted in a future release.
Examples
Create a subscription to a remote server that replicates tables in
the publications
mypublication
and
insert_only
and starts replicating immediately on
commit:
CREATE SUBSCRIPTION mysub CONNECTION 'host=192.168.1.50 port=5432 user=foo dbname=foodb' PUBLICATION mypublication, insert_only;
Create a subscription to a remote server that replicates tables in
the
insert_only
publication and does not start replicating
until enabled at a later time.
CREATE SUBSCRIPTION mysub CONNECTION 'host=192.168.1.50 port=5432 user=foo dbname=foodb' PUBLICATION insert_only WITH (enabled = false);
Compatibility
CREATE SUBSCRIPTION
is a
PostgreSQL
extension.