CREATE SUBSCRIPTION(7) PostgreSQL 15.7 Documentation CREATE SUBSCRIPTION(7)
NAME
CREATE_SUBSCRIPTION - define a new subscription
SYNOPSIS
CREATE SUBSCRIPTION subscription_name
CONNECTION 'conninfo'
PUBLICATION publication_name [, ...]
[ WITH ( subscription_parameter [= value] [, ... ] ) ]
DESCRIPTION
CREATE 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 Section 31.2 and Chapter 31.
PARAMETERS
subscription_name
The name of the new subscription.
CONNECTION 'conninfo'
The libpq connection string defining how to connect to the
publisher database. 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 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 Notes 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 synchronous_commit
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 Section 31.9 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 Section 31.2.2 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);
COMPATIBILITY
CREATE SUBSCRIPTION is a PostgreSQL extension.
SEE ALSO
ALTER SUBSCRIPTION (ALTER_SUBSCRIPTION(7)), DROP SUBSCRIPTION
(DROP_SUBSCRIPTION(7)), CREATE PUBLICATION (CREATE_PUBLICATION(7)),
ALTER PUBLICATION (ALTER_PUBLICATION(7))
PostgreSQL 15.7 2024 CREATE SUBSCRIPTION(7)
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