CREATE SUBSCRIPTIONCREATE SUBSCRIPTION7SQL - Language StatementsCREATE SUBSCRIPTIONdefine a new subscription
CREATE SUBSCRIPTION subscription_name
CONNECTION 'conninfo'
PUBLICATION publication_name [, ...]
[ WITH ( subscription_parameter [= value] [, ... ] ) ]
DescriptionCREATE SUBSCRIPTION adds a new logical-replication
subscription. The subscription name must be distinct from the name of
any existing subscription in the current database.
A subscription represents a replication connection to the publisher.
Hence, in addition to adding definitions in the local catalogs, this
command normally 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,
unless the subscription is initially disabled.
Additional information about subscriptions and logical replication as a
whole is available at and
.
Parameterssubscription_name
The name of the new subscription.
CONNECTION 'conninfo'
The libpq connection string defining how
to connect to the publisher database. 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 control what happens during subscription creation:
connect (boolean)
Specifies whether the CREATE SUBSCRIPTION
command should connect to the publisher at all. The default
is true. Setting this to
false will force the values of
create_slot, enabled and
copy_data to false.
(You cannot combine setting connect
to false with
setting create_slot, enabled,
or copy_data to true.)
Since no connection is made when this option is
false, no tables are subscribed, and so
after you enable the subscription nothing will be replicated.
You will need to then run
ALTER SUBSCRIPTION ... REFRESH PUBLICATION
for tables to be subscribed.
create_slot (boolean)
Specifies whether the command should create the replication slot on
the publisher. The default is true.
If set to false, you are responsible for
creating the publisher's slot in some other way.
enabled (boolean)
Specifies whether the subscription should be actively replicating
or whether it should just be set up but not started yet. The default
is true.
slot_name (string)
Name of the publisher's replication slot to use. The default is
to use the name of the subscription for the slot name.
Setting slot_name to NONE
means there will be no replication slot
associated with the subscription. Use this when you will be
creating the replication slot later manually. Such
subscriptions must also have both enabled and
create_slot set to false.
The following parameters control the subscription's replication
behavior after it has been created:
binary (boolean)
Specifies whether the subscription will request the publisher to
send the data in binary format (as opposed to text).
The default is false.
Even when this option is enabled, only data types having
binary send and receive functions will be transferred in binary.
When doing cross-version replication, it could be that the
publisher has a binary send function for some data type, but the
subscriber lacks a binary receive function for that type. In
such a case, data transfer will fail, and
the binary option cannot be used.
copy_data (boolean)
Specifies whether to copy pre-existing data in the publications
that are being subscribed to when the replication starts.
The default is true.
If the publications contain WHERE clauses, it
will affect what data is copied. Refer to the
for details.
streaming (boolean)
Specifies whether to enable streaming of in-progress transactions
for this subscription. By default, all transactions
are fully decoded on the publisher and only then sent to the
subscriber as a whole.
synchronous_commit (enum)
The value of this parameter overrides the
setting within this
subscription's apply worker processes. 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.
two_phase (boolean)
Specifies whether two-phase commit is enabled for this subscription.
The default is false.
When two-phase commit is enabled, prepared transactions are sent
to the subscriber at the time of PREPARE
TRANSACTION, and are processed as two-phase
transactions on the subscriber too. Otherwise, prepared
transactions are sent to the subscriber only when committed, and
are then processed immediately by the subscriber.
The implementation of two-phase commit requires that replication
has successfully finished the initial table synchronization
phase. So even when two_phase is enabled for a
subscription, the internal two-phase state remains
temporarily pending until the initialization phase
completes. See column subtwophasestate
of pg_subscription
to know the actual two-phase state.
disable_on_error (boolean)
Specifies whether the subscription should be automatically disabled
if any errors are detected by subscription workers during data
replication from the publisher. The default is
false.
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.
If any table in the publication has a WHERE clause, rows
for which the expression
evaluates to false or null will not be published. If the subscription has
several publications in which the same table has been published with
different WHERE clauses, a row will be published if any
of the expressions (referring to that publish operation) are satisfied. In
the case of different WHERE clauses, if one of the
publications has no WHERE clause (referring to that
publish operation) or the publication is declared as
FOR ALL TABLES or
FOR TABLES IN SCHEMA, rows are always published
regardless of the definition of the other expressions.
If the subscriber is a PostgreSQL version before
15, then any row filtering is ignored during the initial data synchronization
phase. For this case, the user might want to consider deleting any initially
copied data that would be incompatible with subsequent filtering.
Because initial data synchronization does not take into account the publication
publish parameter when copying existing table data, some rows
may be copied that would not be replicated using DML. See
for examples.
Subscriptions having several publications in which the same table has been
published with different column lists are not supported.
We allow non-existent publications to be specified so that users can add
those later. This means
pg_subscription
can have non-existent publications.
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);
CompatibilityCREATE SUBSCRIPTION is a PostgreSQL
extension.
See Also