CREATE SUBSCRIPTION
CREATE SUBSCRIPTION
7
SQL - Language Statements
CREATE SUBSCRIPTION
define a new subscription
CREATE SUBSCRIPTION subscription_name
CONNECTION 'conninfo'
PUBLICATION publication_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 and
.
Parameters
subscription_name
The name of the new subscription.
CONNECTION 'conninfo'
The connection string to the publisher. For details
see .
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 to
NONE, 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 both enabled and
create_slot set to false.
synchronous_commit (enum)
The value of this parameter overrides the
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 sent again 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 to
off when the subscription is used for
synchronous replication might increase the latency for
COMMIT on the publisher. In this scenario, it
can be advantageous to set synchronous_commit
to local or higher.
connect (boolean)
Specifies whether the CREATE SUBSCRIPTION
should connect to the publisher at all. Setting this to
false will change default values of
enabled, create_slot and
copy_data to false.
It is not allowed to combine connect set to
false and enabled,
create_slot, or copy_data
set to true.
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 run
ALTER SUBSCRIPTION ... REFRESH PUBLICATION in order
for tables to be subscribed.
Notes
See 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.
See Also