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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>CREATE SUBSCRIPTION</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="sql-createstatistics.html" title="CREATE STATISTICS" /><link rel="next" href="sql-createtable.html" title="CREATE TABLE" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">CREATE SUBSCRIPTION</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-createstatistics.html" title="CREATE STATISTICS">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><th width="60%" align="center">SQL Commands</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.7 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="sql-createtable.html" title="CREATE TABLE">Next</a></td></tr></table><hr /></div><div class="refentry" id="SQL-CREATESUBSCRIPTION"><div class="titlepage"></div><a id="id-1.9.3.84.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">CREATE SUBSCRIPTION</span></h2><p>CREATE SUBSCRIPTION — define a new subscription</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">
CREATE SUBSCRIPTION <em class="replaceable"><code>subscription_name</code></em>
CONNECTION '<em class="replaceable"><code>conninfo</code></em>'
PUBLICATION <em class="replaceable"><code>publication_name</code></em> [, ...]
[ WITH ( <em class="replaceable"><code>subscription_parameter</code></em> [= <em class="replaceable"><code>value</code></em>] [, ... ] ) ]
</pre></div><div class="refsect1" id="id-1.9.3.84.5"><h2>Description</h2><p>
<code class="command">CREATE SUBSCRIPTION</code> adds a new logical-replication
subscription. The subscription name must be distinct from the name of
any existing subscription in the current database.
</p><p>
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.
</p><p>
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.
</p><p>
Additional information about subscriptions and logical replication as a
whole is available at <a class="xref" href="logical-replication-subscription.html" title="31.2. Subscription">Section 31.2</a> and
<a class="xref" href="logical-replication.html" title="Chapter 31. Logical Replication">Chapter 31</a>.
</p></div><div class="refsect1" id="id-1.9.3.84.6"><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>subscription_name</code></em></span></dt><dd><p>
The name of the new subscription.
</p></dd><dt><span class="term"><code class="literal">CONNECTION '<em class="replaceable"><code>conninfo</code></em>'</code></span></dt><dd><p>
The <span class="application">libpq</span> connection string defining how
to connect to the publisher database. For details see
<a class="xref" href="libpq-connect.html#LIBPQ-CONNSTRING" title="34.1.1. Connection Strings">Section 34.1.1</a>.
</p></dd><dt><span class="term"><code class="literal">PUBLICATION <em class="replaceable"><code>publication_name</code></em> [, ...]</code></span></dt><dd><p>
Names of the publications on the publisher to subscribe to.
</p></dd><dt><span class="term"><code class="literal">WITH ( <em class="replaceable"><code>subscription_parameter</code></em> [= <em class="replaceable"><code>value</code></em>] [, ... ] )</code></span></dt><dd><p>
This clause specifies optional parameters for a subscription.
</p><p>
The following parameters control what happens during subscription creation:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">connect</code> (<code class="type">boolean</code>)</span></dt><dd><p>
Specifies whether the <code class="command">CREATE SUBSCRIPTION</code>
command should connect to the publisher at all. The default
is <code class="literal">true</code>. Setting this to
<code class="literal">false</code> will force the values of
<code class="literal">create_slot</code>, <code class="literal">enabled</code> and
<code class="literal">copy_data</code> to <code class="literal">false</code>.
(You cannot combine setting <code class="literal">connect</code>
to <code class="literal">false</code> with
setting <code class="literal">create_slot</code>, <code class="literal">enabled</code>,
or <code class="literal">copy_data</code> to <code class="literal">true</code>.)
</p><p>
Since no connection is made when this option is
<code class="literal">false</code>, no tables are subscribed, and so
after you enable the subscription nothing will be replicated.
You will need to then run
<code class="literal">ALTER SUBSCRIPTION ... REFRESH PUBLICATION</code>
for tables to be subscribed.
</p></dd><dt><span class="term"><code class="literal">create_slot</code> (<code class="type">boolean</code>)</span></dt><dd><p>
Specifies whether the command should create the replication slot on
the publisher. The default is <code class="literal">true</code>.
If set to <code class="literal">false</code>, you are responsible for
creating the publisher's slot in some other way.
</p></dd><dt><span class="term"><code class="literal">enabled</code> (<code class="type">boolean</code>)</span></dt><dd><p>
Specifies whether the subscription should be actively replicating
or whether it should just be set up but not started yet. The default
is <code class="literal">true</code>.
</p></dd><dt><span class="term"><code class="literal">slot_name</code> (<code class="type">string</code>)</span></dt><dd><p>
Name of the publisher's replication slot to use. The default is
to use the name of the subscription for the slot name.
</p><p>
Setting <code class="literal">slot_name</code> to <code class="literal">NONE</code>
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 <code class="literal">enabled</code> and
<code class="literal">create_slot</code> set to <code class="literal">false</code>.
</p></dd></dl></div><p>
</p><p>
The following parameters control the subscription's replication
behavior after it has been created:
</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">binary</code> (<code class="type">boolean</code>)</span></dt><dd><p>
Specifies whether the subscription will request the publisher to
send the data in binary format (as opposed to text).
The default is <code class="literal">false</code>.
Even when this option is enabled, only data types having
binary send and receive functions will be transferred in binary.
</p><p>
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 <code class="literal">binary</code> option cannot be used.
</p></dd><dt><span class="term"><code class="literal">copy_data</code> (<code class="type">boolean</code>)</span></dt><dd><p>
Specifies whether to copy pre-existing data in the publications
that are being subscribed to when the replication starts.
The default is <code class="literal">true</code>.
</p><p>
If the publications contain <code class="literal">WHERE</code> clauses, it
will affect what data is copied. Refer to the
<a class="xref" href="sql-createsubscription.html#SQL-CREATESUBSCRIPTION-NOTES" title="Notes">Notes</a> for details.
</p></dd><dt><span class="term"><code class="literal">streaming</code> (<code class="type">boolean</code>)</span></dt><dd><p>
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.
</p></dd><dt><span class="term"><code class="literal">synchronous_commit</code> (<code class="type">enum</code>)</span></dt><dd><p>
The value of this parameter overrides the
<a class="xref" href="runtime-config-wal.html#GUC-SYNCHRONOUS-COMMIT">synchronous_commit</a> setting within this
subscription's apply worker processes. The default value
is <code class="literal">off</code>.
</p><p>
It is safe to use <code class="literal">off</code> for logical replication:
If the subscriber loses transactions because of missing
synchronization, the data will be sent again from the publisher.
</p><p>
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
<code class="literal">synchronous_commit</code> for the subscriber to
<code class="literal">off</code> when the subscription is used for
synchronous replication might increase the latency for
<code class="command">COMMIT</code> on the publisher. In this scenario, it
can be advantageous to set <code class="literal">synchronous_commit</code>
to <code class="literal">local</code> or higher.
</p></dd><dt><span class="term"><code class="literal">two_phase</code> (<code class="type">boolean</code>)</span></dt><dd><p>
Specifies whether two-phase commit is enabled for this subscription.
The default is <code class="literal">false</code>.
</p><p>
When two-phase commit is enabled, prepared transactions are sent
to the subscriber at the time of <code class="command">PREPARE
TRANSACTION</code>, 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.
</p><p>
The implementation of two-phase commit requires that replication
has successfully finished the initial table synchronization
phase. So even when <code class="literal">two_phase</code> is enabled for a
subscription, the internal two-phase state remains
temporarily <span class="quote">“<span class="quote">pending</span>”</span> until the initialization phase
completes. See column <code class="structfield">subtwophasestate</code>
of <a class="link" href="catalog-pg-subscription.html" title="53.54. pg_subscription"><code class="structname">pg_subscription</code></a>
to know the actual two-phase state.
</p></dd><dt><span class="term"><code class="literal">disable_on_error</code> (<code class="type">boolean</code>)</span></dt><dd><p>
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
<code class="literal">false</code>.
</p></dd></dl></div></dd></dl></div></div><div class="refsect1" id="SQL-CREATESUBSCRIPTION-NOTES"><h2>Notes</h2><p>
See <a class="xref" href="logical-replication-security.html" title="31.9. Security">Section 31.9</a> for details on
how to configure access control between the subscription and the
publication instance.
</p><p>
When creating a replication slot (the default behavior), <code class="command">CREATE
SUBSCRIPTION</code> cannot be executed inside a transaction block.
</p><p>
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 <code class="command">CREATE
SUBSCRIPTION</code> call will hang. To make this work, create the
replication slot separately (using the
function <code class="function">pg_create_logical_replication_slot</code> with the
plugin name <code class="literal">pgoutput</code>) and create the subscription using
the parameter <code class="literal">create_slot = false</code>. This is an
implementation restriction that might be lifted in a future release.
</p><p>
If any table in the publication has a <code class="literal">WHERE</code> clause, rows
for which the <em class="replaceable"><code>expression</code></em>
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 <code class="literal">WHERE</code> clauses, a row will be published if any
of the expressions (referring to that publish operation) are satisfied. In
the case of different <code class="literal">WHERE</code> clauses, if one of the
publications has no <code class="literal">WHERE</code> clause (referring to that
publish operation) or the publication is declared as
<code class="literal">FOR ALL TABLES</code> or
<code class="literal">FOR TABLES IN SCHEMA</code>, rows are always published
regardless of the definition of the other expressions.
If the subscriber is a <span class="productname">PostgreSQL</span> 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
<code class="literal">publish</code> parameter when copying existing table data, some rows
may be copied that would not be replicated using DML. See
<a class="xref" href="logical-replication-subscription.html#LOGICAL-REPLICATION-SUBSCRIPTION-EXAMPLES" title="31.2.2. Examples">Section 31.2.2</a> for examples.
</p><p>
Subscriptions having several publications in which the same table has been
published with different column lists are not supported.
</p><p>
We allow non-existent publications to be specified so that users can add
those later. This means
<a class="link" href="catalog-pg-subscription.html" title="53.54. pg_subscription"><code class="structname">pg_subscription</code></a>
can have non-existent publications.
</p></div><div class="refsect1" id="id-1.9.3.84.8"><h2>Examples</h2><p>
Create a subscription to a remote server that replicates tables in
the publications <code class="literal">mypublication</code> and
<code class="literal">insert_only</code> and starts replicating immediately on
commit:
</p><pre class="programlisting">
CREATE SUBSCRIPTION mysub
CONNECTION 'host=192.168.1.50 port=5432 user=foo dbname=foodb'
PUBLICATION mypublication, insert_only;
</pre><p>
</p><p>
Create a subscription to a remote server that replicates tables in
the <code class="literal">insert_only</code> publication and does not start replicating
until enabled at a later time.
</p><pre class="programlisting">
CREATE SUBSCRIPTION mysub
CONNECTION 'host=192.168.1.50 port=5432 user=foo dbname=foodb'
PUBLICATION insert_only
WITH (enabled = false);
</pre></div><div class="refsect1" id="id-1.9.3.84.9"><h2>Compatibility</h2><p>
<code class="command">CREATE SUBSCRIPTION</code> is a <span class="productname">PostgreSQL</span>
extension.
</p></div><div class="refsect1" id="id-1.9.3.84.10"><h2>See Also</h2><span class="simplelist"><a class="xref" href="sql-altersubscription.html" title="ALTER SUBSCRIPTION"><span class="refentrytitle">ALTER SUBSCRIPTION</span></a>, <a class="xref" href="sql-dropsubscription.html" title="DROP SUBSCRIPTION"><span class="refentrytitle">DROP SUBSCRIPTION</span></a>, <a class="xref" href="sql-createpublication.html" title="CREATE PUBLICATION"><span class="refentrytitle">CREATE PUBLICATION</span></a>, <a class="xref" href="sql-alterpublication.html" title="ALTER PUBLICATION"><span class="refentrytitle">ALTER PUBLICATION</span></a></span></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="sql-createstatistics.html" title="CREATE STATISTICS">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="sql-createtable.html" title="CREATE TABLE">Next</a></td></tr><tr><td width="40%" align="left" valign="top">CREATE STATISTICS </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 15.7 Documentation">Home</a></td><td width="40%" align="right" valign="top"> CREATE TABLE</td></tr></table></div></body></html>
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