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diff --git a/doc/src/sgml/html/logicaldecoding-synchronous.html b/doc/src/sgml/html/logicaldecoding-synchronous.html new file mode 100644 index 0000000..6bfef14 --- /dev/null +++ b/doc/src/sgml/html/logicaldecoding-synchronous.html @@ -0,0 +1,50 @@ +<?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>49.8. Synchronous Replication Support for Logical Decoding</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="logicaldecoding-writer.html" title="49.7. Logical Decoding Output Writers" /><link rel="next" href="logicaldecoding-streaming.html" title="49.9. Streaming of Large Transactions for Logical Decoding" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">49.8. Synchronous Replication Support for Logical Decoding</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="logicaldecoding-writer.html" title="49.7. Logical Decoding Output Writers">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="logicaldecoding.html" title="Chapter 49. Logical Decoding">Up</a></td><th width="60%" align="center">Chapter 49. Logical Decoding</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 15.5 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="logicaldecoding-streaming.html" title="49.9. Streaming of Large Transactions for Logical Decoding">Next</a></td></tr></table><hr /></div><div class="sect1" id="LOGICALDECODING-SYNCHRONOUS"><div class="titlepage"><div><div><h2 class="title" style="clear: both">49.8. Synchronous Replication Support for Logical Decoding</h2></div></div></div><div class="toc"><dl class="toc"><dt><span class="sect2"><a href="logicaldecoding-synchronous.html#id-1.8.14.14.2">49.8.1. Overview</a></span></dt><dt><span class="sect2"><a href="logicaldecoding-synchronous.html#LOGICALDECODING-SYNCHRONOUS-CAVEATS">49.8.2. Caveats</a></span></dt></dl></div><div class="sect2" id="id-1.8.14.14.2"><div class="titlepage"><div><div><h3 class="title">49.8.1. Overview</h3></div></div></div><p> + Logical decoding can be used to build + <a class="link" href="warm-standby.html#SYNCHRONOUS-REPLICATION" title="27.2.8. Synchronous Replication">synchronous + replication</a> solutions with the same user interface as synchronous + replication for <a class="link" href="warm-standby.html#STREAMING-REPLICATION" title="27.2.5. Streaming Replication">streaming + replication</a>. To do this, the streaming replication interface + (see <a class="xref" href="logicaldecoding-walsender.html" title="49.3. Streaming Replication Protocol Interface">Section 49.3</a>) must be used to stream out + data. Clients have to send <code class="literal">Standby status update (F)</code> + (see <a class="xref" href="protocol-replication.html" title="55.4. Streaming Replication Protocol">Section 55.4</a>) messages, just like streaming + replication clients do. + </p><div class="note"><h3 class="title">Note</h3><p> + A synchronous replica receiving changes via logical decoding will work in + the scope of a single database. Since, in contrast to + that, <em class="parameter"><code>synchronous_standby_names</code></em> currently is + server wide, this means this technique will not work properly if more + than one database is actively used. + </p></div></div><div class="sect2" id="LOGICALDECODING-SYNCHRONOUS-CAVEATS"><div class="titlepage"><div><div><h3 class="title">49.8.2. Caveats</h3></div></div></div><p> + In synchronous replication setup, a deadlock can happen, if the transaction + has locked [user] catalog tables exclusively. See + <a class="xref" href="logicaldecoding-output-plugin.html#LOGICALDECODING-CAPABILITIES" title="49.6.2. Capabilities">Section 49.6.2</a> for information on user + catalog tables. This is because logical decoding of transactions can lock + catalog tables to access them. To avoid this users must refrain from taking + an exclusive lock on [user] catalog tables. This can happen in the following + ways: + + </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p> + Issuing an explicit <code class="command">LOCK</code> on <code class="structname">pg_class</code> + in a transaction. + </p></li><li class="listitem"><p> + Perform <code class="command">CLUSTER</code> on <code class="structname">pg_class</code> in + a transaction. + </p></li><li class="listitem"><p> + <code class="command">PREPARE TRANSACTION</code> after <code class="command">LOCK</code> command + on <code class="structname">pg_class</code> and allow logical decoding of two-phase + transactions. + </p></li><li class="listitem"><p> + <code class="command">PREPARE TRANSACTION</code> after <code class="command">CLUSTER</code> + command on <code class="structname">pg_trigger</code> and allow logical decoding of + two-phase transactions. This will lead to deadlock only when published table + have a trigger. + </p></li><li class="listitem"><p> + Executing <code class="command">TRUNCATE</code> on [user] catalog table in a + transaction. + </p></li></ul></div><p> + + Note that these commands that can cause deadlock apply to not only explicitly + indicated system catalog tables above but also to any other [user] catalog + table. + </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="logicaldecoding-writer.html" title="49.7. Logical Decoding Output Writers">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="logicaldecoding.html" title="Chapter 49. Logical Decoding">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="logicaldecoding-streaming.html" title="49.9. Streaming of Large Transactions for Logical Decoding">Next</a></td></tr><tr><td width="40%" align="left" valign="top">49.7. 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