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  1. <?xml version="1.0" encoding="UTF-8" standalone="no"?>

  2. <!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 V1.79.1" /><link rel="prev" href="sql-createstatistics.html" title="CREATE STATISTICS" /><link rel="next" href="sql-createtable.html" title="CREATE TABLE" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" 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 12.4 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></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">

  3. CREATE SUBSCRIPTION <em class="replaceable"><code>subscription_name</code></em>

  4.     CONNECTION '<em class="replaceable"><code>conninfo</code></em>'

  5.     PUBLICATION <em class="replaceable"><code>publication_name</code></em> [, ...]

  6.     [ WITH ( <em class="replaceable"><code>subscription_parameter</code></em> [= <em class="replaceable"><code>value</code></em>] [, ... ] ) ]

  7. </pre></div><div class="refsect1" id="id-1.9.3.84.5"><h2>Description</h2><p>

  8.    <code class="command">CREATE SUBSCRIPTION</code> adds a new subscription for the

  9.    current database.  The subscription name must be distinct from the name of

  10.    any existing subscription in the database.

  11.   </p><p>

  12.    The subscription represents a replication connection to the publisher.  As

  13.    such this command does not only add definitions in the local catalogs but

  14.    also creates a replication slot on the publisher.

  15.   </p><p>

  16.    A logical replication worker will be started to replicate data for the new

  17.    subscription at the commit of the transaction where this command is run.

  18.   </p><p>

  19.    Additional information about subscriptions and logical replication as a

  20.    whole is available at <a class="xref" href="logical-replication-subscription.html" title="30.2. Subscription">Section 30.2</a> and

  21.    <a class="xref" href="logical-replication.html" title="Chapter 30. Logical Replication">Chapter 30</a>.

  22.   </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>

  23.       The name of the new subscription.

  24.      </p></dd><dt><span class="term"><code class="literal">CONNECTION '<em class="replaceable"><code>conninfo</code></em>'</code></span></dt><dd><p>

  25.       The connection string to the publisher.  For details

  26.       see <a class="xref" href="libpq-connect.html#LIBPQ-CONNSTRING" title="33.1.1. Connection Strings">Section 33.1.1</a>.

  27.      </p></dd><dt><span class="term"><code class="literal">PUBLICATION <em class="replaceable"><code>publication_name</code></em></code></span></dt><dd><p>

  28.       Names of the publications on the publisher to subscribe to.

  29.      </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>

  30.       This clause specifies optional parameters for a subscription.  The

  31.       following parameters are supported:

  32. 

  33.       </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">copy_data</code> (<code class="type">boolean</code>)</span></dt><dd><p>

  34.           Specifies whether the existing data in the publications that are

  35.           being subscribed to should be copied once the replication starts.

  36.           The default is <code class="literal">true</code>.

  37.          </p></dd><dt><span class="term"><code class="literal">create_slot</code> (<code class="type">boolean</code>)</span></dt><dd><p>

  38.           Specifies whether the command should create the replication slot on

  39.           the publisher.  The default is <code class="literal">true</code>.

  40.          </p></dd><dt><span class="term"><code class="literal">enabled</code> (<code class="type">boolean</code>)</span></dt><dd><p>

  41.           Specifies whether the subscription should be actively replicating,

  42.           or whether it should be just setup but not started yet.  The default

  43.           is <code class="literal">true</code>.

  44.          </p></dd><dt><span class="term"><code class="literal">slot_name</code> (<code class="type">string</code>)</span></dt><dd><p>

  45.           Name of the replication slot to use.  The default behavior is to

  46.           use the name of the subscription for the slot name.

  47.          </p><p>

  48.           When <code class="literal">slot_name</code> is set to

  49.           <code class="literal">NONE</code>, there will be no replication slot

  50.           associated with the subscription.  This can be used if the

  51.           replication slot will be created later manually.  Such

  52.           subscriptions must also have both <code class="literal">enabled</code> and

  53.           <code class="literal">create_slot</code> set to <code class="literal">false</code>.

  54.          </p></dd><dt><span class="term"><code class="literal">synchronous_commit</code> (<code class="type">enum</code>)</span></dt><dd><p>

  55.           The value of this parameter overrides the

  56.           <a class="xref" href="runtime-config-wal.html#GUC-SYNCHRONOUS-COMMIT">synchronous_commit</a> setting.  The default

  57.           value is <code class="literal">off</code>.

  58.          </p><p>

  59.           It is safe to use <code class="literal">off</code> for logical replication:

  60.           If the subscriber loses transactions because of missing

  61.           synchronization, the data will be resent from the publisher.

  62.          </p><p>

  63.           A different setting might be appropriate when doing synchronous

  64.           logical replication.  The logical replication workers report the

  65.           positions of writes and flushes to the publisher, and when using

  66.           synchronous replication, the publisher will wait for the actual

  67.           flush.  This means that setting

  68.           <code class="literal">synchronous_commit</code> for the subscriber to

  69.           <code class="literal">off</code> when the subscription is used for

  70.           synchronous replication might increase the latency for

  71.           <code class="command">COMMIT</code> on the publisher.  In this scenario, it

  72.           can be advantageous to set <code class="literal">synchronous_commit</code>

  73.           to <code class="literal">local</code> or higher.

  74.          </p></dd><dt><span class="term"><code class="literal">connect</code> (<code class="type">boolean</code>)</span></dt><dd><p>

  75.           Specifies whether the <code class="command">CREATE SUBSCRIPTION</code>

  76.           should connect to the publisher at all.  Setting this to

  77.           <code class="literal">false</code> will change default values of

  78.           <code class="literal">enabled</code>, <code class="literal">create_slot</code> and

  79.           <code class="literal">copy_data</code> to <code class="literal">false</code>.

  80.          </p><p>

  81.           It is not allowed to combine <code class="literal">connect</code> set to

  82.           <code class="literal">false</code> and <code class="literal">enabled</code>,

  83.           <code class="literal">create_slot</code>, or <code class="literal">copy_data</code>

  84.           set to <code class="literal">true</code>.

  85.          </p><p>

  86.           Since no connection is made when this option is set

  87.           to <code class="literal">false</code>, the tables are not subscribed, and so

  88.           after you enable the subscription nothing will be replicated.

  89.           It is required to run

  90.           <code class="literal">ALTER SUBSCRIPTION ... REFRESH PUBLICATION</code> in order

  91.           for tables to be subscribed.

  92.          </p></dd></dl></div><p>

  93.      </p></dd></dl></div></div><div class="refsect1" id="id-1.9.3.84.7"><h2>Notes</h2><p>

  94.    See <a class="xref" href="logical-replication-security.html" title="30.7. Security">Section 30.7</a> for details on

  95.    how to configure access control between the subscription and the

  96.    publication instance.

  97.   </p><p>

  98.    When creating a replication slot (the default behavior), <code class="command">CREATE

  99.    SUBSCRIPTION</code> cannot be executed inside a transaction block.

  100.   </p><p>

  101.    Creating a subscription that connects to the same database cluster (for

  102.    example, to replicate between databases in the same cluster or to replicate

  103.    within the same database) will only succeed if the replication slot is not

  104.    created as part of the same command.  Otherwise, the <code class="command">CREATE

  105.    SUBSCRIPTION</code> call will hang.  To make this work, create the

  106.    replication slot separately (using the

  107.    function <code class="function">pg_create_logical_replication_slot</code> with the

  108.    plugin name <code class="literal">pgoutput</code>) and create the subscription using

  109.    the parameter <code class="literal">create_slot = false</code>.  This is an

  110.    implementation restriction that might be lifted in a future release.

  111.   </p></div><div class="refsect1" id="id-1.9.3.84.8"><h2>Examples</h2><p>

  112.    Create a subscription to a remote server that replicates tables in

  113.    the publications <code class="literal">mypublication</code> and

  114.    <code class="literal">insert_only</code> and starts replicating immediately on

  115.    commit:

  116. </p><pre class="programlisting">

  117. CREATE SUBSCRIPTION mysub

  118.          CONNECTION 'host=192.168.1.50 port=5432 user=foo dbname=foodb'

  119.         PUBLICATION mypublication, insert_only;

  120. </pre><p>

  121.   </p><p>

  122.    Create a subscription to a remote server that replicates tables in

  123.    the <code class="literal">insert_only</code> publication and does not start replicating

  124.    until enabled at a later time.

  125. </p><pre class="programlisting">

  126. CREATE SUBSCRIPTION mysub

  127.          CONNECTION 'host=192.168.1.50 port=5432 user=foo dbname=foodb'

  128.         PUBLICATION insert_only

  129.                WITH (enabled = false);

  130. </pre></div><div class="refsect1" id="id-1.9.3.84.9"><h2>Compatibility</h2><p>

  131.    <code class="command">CREATE SUBSCRIPTION</code> is a <span class="productname">PostgreSQL</span>

  132.    extension.

  133.   </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">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sql-commands.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="sql-createtable.html">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">Home</a></td><td width="40%" align="right" valign="top"> CREATE TABLE</td></tr></table></div></body></html>
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