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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>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 id="docContent" class="container-fluid col-10"><div 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 16.3 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 /></div><div class="sect1" id="LOGICAL-REPLICATION-PUBLICATION"><div class="titlepage"><div><div><h2 class="title" style="clear: both">31.1. Publication <a href="#LOGICAL-REPLICATION-PUBLICATION" class="id_link">#</a></h2></div></div></div><p>3   A <em class="firstterm">publication</em> can be defined on any physical4   replication primary.  The node where a publication is defined is referred to5   as <em class="firstterm">publisher</em>.  A publication is a set of changes6   generated from a table or a group of tables, and might also be described as7   a change set or replication set.  Each publication exists in only one database.8  </p><p>9   Publications are different from schemas and do not affect how the table is10   accessed.  Each table can be added to multiple publications if needed.11   Publications may currently only contain tables and all tables in schema.12   Objects must be added explicitly, except when a publication is created for13   <code class="literal">ALL TABLES</code>.14  </p><p>15   Publications can choose to limit the changes they produce to16   any combination of <code class="command">INSERT</code>, <code class="command">UPDATE</code>,17   <code class="command">DELETE</code>, and <code class="command">TRUNCATE</code>, similar to how triggers are fired by18   particular event types. By default, all operation types are replicated.19   These publication specifications apply only for DML operations; they do not affect the initial20   data synchronization copy. (Row filters have no effect for21   <code class="command">TRUNCATE</code>. See <a class="xref" href="logical-replication-row-filter.html" title="31.3. Row Filters">Section 31.3</a>).22  </p><p>23   A published table must have a <em class="firstterm">replica identity</em> configured in24   order to be able to replicate <code class="command">UPDATE</code>25   and <code class="command">DELETE</code> operations, so that appropriate rows to26   update or delete can be identified on the subscriber side.  By default,27   this is the primary key, if there is one.  Another unique index (with28   certain additional requirements) can also be set to be the replica29   identity.  If the table does not have any suitable key, then it can be set30   to replica identity <code class="literal">FULL</code>, which means the entire row becomes31   the key.  When replica identity <code class="literal">FULL</code> is specified,32   indexes can be used on the subscriber side for searching the rows.  Candidate33   indexes must be btree, non-partial, and the leftmost index field must be a34   column (not an expression) that references the published table column.  These35   restrictions on the non-unique index properties adhere to some of the36   restrictions that are enforced for primary keys.  If there are no such37   suitable indexes, the search on the subscriber side can be very inefficient,38   therefore replica identity <code class="literal">FULL</code> should only be used as a39   fallback if no other solution is possible.  If a replica identity other40   than <code class="literal">FULL</code> is set on the publisher side, a replica identity41   comprising the same or fewer columns must also be set on the subscriber42   side.  See <a class="xref" href="sql-altertable.html#SQL-ALTERTABLE-REPLICA-IDENTITY"><code class="literal">REPLICA IDENTITY</code></a> for details on43   how to set the replica identity.  If a table without a replica identity is44   added to a publication that replicates <code class="command">UPDATE</code>45   or <code class="command">DELETE</code> operations then46   subsequent <code class="command">UPDATE</code> or <code class="command">DELETE</code>47   operations will cause an error on the publisher.  <code class="command">INSERT</code>48   operations can proceed regardless of any replica identity.49  </p><p>50   Every publication can have multiple subscribers.51  </p><p>52   A publication is created using the <a class="link" href="sql-createpublication.html" title="CREATE PUBLICATION"><code class="command">CREATE PUBLICATION</code></a>53   command and may later be altered or dropped using corresponding commands.54  </p><p>55   The individual tables can be added and removed dynamically using56   <a class="link" href="sql-alterpublication.html" title="ALTER PUBLICATION"><code class="command">ALTER PUBLICATION</code></a>.  Both the <code class="literal">ADD57   TABLE</code> and <code class="literal">DROP TABLE</code> operations are58   transactional; so the table will start or stop replicating at the correct59   snapshot once the transaction has committed.60  </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" title="Chapter 31. Logical Replication">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="logical-replication.html" title="Chapter 31. Logical Replication">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="logical-replication-subscription.html" title="31.2. Subscription">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" title="PostgreSQL 16.3 Documentation">Home</a></td><td width="40%" align="right" valign="top"> 31.2. Subscription</td></tr></table></div></body></html>