<?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>31.1. Publication</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="logical-replication.html" title="Chapter 31. Logical Replication" /><link rel="next" href="logical-replication-subscription.html" title="31.2. Subscription" /></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">31.1. Publication</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="logical-replication.html" title="Chapter 31. Logical Replication">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="logical-replication.html" title="Chapter 31. Logical Replication">Up</a></td><th width="60%" align="center">Chapter 31. Logical Replication</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 11.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="logical-replication-subscription.html" title="31.2. Subscription">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="LOGICAL-REPLICATION-PUBLICATION"><div class="titlepage"><div><div><h2 class="title" style="clear: both">31.1. Publication</h2></div></div></div><p> A <em class="firstterm">publication</em> can be defined on any physical replication master. The node where a publication is defined is referred to as <em class="firstterm">publisher</em>. A publication is a set of changes generated from a table or a group of tables, and might also be described as a change set or replication set. Each publication exists in only one database. </p><p> Publications are different from schemas and do not affect how the table is accessed. Each table can be added to multiple publications if needed. Publications may currently only contain tables. Objects must be added explicitly, except when a publication is created for <code class="literal">ALL TABLES</code>. </p><p> Publications can choose to limit the changes they produce to any combination of <code class="command">INSERT</code>, <code class="command">UPDATE</code>, <code class="command">DELETE</code>, and <code class="command">TRUNCATE</code>, similar to how triggers are fired by particular event types. By default, all operation types are replicated. </p><p> A published table must have a <span class="quote">“<span class="quote">replica identity</span>”</span> configured in order to be able to replicate <code class="command">UPDATE</code> and <code class="command">DELETE</code> operations, so that appropriate rows to update or delete can be identified on the subscriber side. By default, this is the primary key, if there is one. Another unique index (with certain additional requirements) can also be set to be the replica identity. If the table does not have any suitable key, then it can be set to replica identity <span class="quote">“<span class="quote">full</span>”</span>, which means the entire row becomes the key. This, however, is very inefficient and should only be used as a fallback if no other solution is possible. If a replica identity other than <span class="quote">“<span class="quote">full</span>”</span> is set on the publisher side, a replica identity comprising the same or fewer columns must also be set on the subscriber side. See <a class="xref" href="sql-altertable.html#SQL-CREATETABLE-REPLICA-IDENTITY"><code class="literal">REPLICA IDENTITY</code></a> for details on how to set the replica identity. If a table without a replica identity is added to a publication that replicates <code class="command">UPDATE</code> or <code class="command">DELETE</code> operations then subsequent <code class="command">UPDATE</code> or <code class="command">DELETE</code> operations will cause an error on the publisher. <code class="command">INSERT</code> operations can proceed regardless of any replica identity. </p><p> Every publication can have multiple subscribers. </p><p> A publication is created using the <a class="xref" href="sql-createpublication.html" title="CREATE PUBLICATION"><span class="refentrytitle">CREATE PUBLICATION</span></a> command and may later be altered or dropped using corresponding commands. </p><p> The individual tables can be added and removed dynamically using <a class="xref" href="sql-alterpublication.html" title="ALTER PUBLICATION"><span class="refentrytitle">ALTER PUBLICATION</span></a>. Both the <code class="literal">ADD TABLE</code> and <code class="literal">DROP TABLE</code> operations are transactional; so the table will start or stop replicating at the correct snapshot once the transaction has committed. </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="logical-replication.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="logical-replication.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="logical-replication-subscription.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 31. Logical Replication </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 31.2. Subscription</td></tr></table></div></body></html>
