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- <!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>30.1. 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 V1.79.1" /><link rel="prev" href="logical-replication.html" title="Chapter 30. Logical Replication" /><link rel="next" href="logical-replication-subscription.html" title="30.2. 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">30.1. Publication</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="logical-replication.html" title="Chapter 30. Logical Replication">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="logical-replication.html" title="Chapter 30. Logical Replication">Up</a></td><th width="60%" align="center">Chapter 30. Logical Replication</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="logical-replication-subscription.html" title="30.2. 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">30.1. 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 30. Logical Replication </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 30.2. Subscription</td></tr></table></div></body></html>
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