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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>14.5. Non-Durable Settings</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="populate.html" title="14.4. Populating a Database" /><link rel="next" href="parallel-query.html" title="Chapter 15. Parallel Query" /></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">14.5. Non-Durable Settings</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="populate.html" title="14.4. Populating a Database">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="performance-tips.html" title="Chapter 14. Performance Tips">Up</a></td><th width="60%" align="center">Chapter 14. Performance Tips</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="parallel-query.html" title="Chapter 15. Parallel Query">Next</a></td></tr></table><hr></hr></div><div class="sect1" id="NON-DURABILITY"><div class="titlepage"><div><div><h2 class="title" style="clear: both">14.5. Non-Durable Settings</h2></div></div></div><a id="id-1.5.13.8.2" class="indexterm"></a><p>
- Durability is a database feature that guarantees the recording of
- committed transactions even if the server crashes or loses
- power. However, durability adds significant database overhead,
- so if your site does not require such a guarantee,
- <span class="productname">PostgreSQL</span> can be configured to run
- much faster. The following are configuration changes you can make
- to improve performance in such cases. Except as noted below, durability
- is still guaranteed in case of a crash of the database software;
- only abrupt operating system stoppage creates a risk of data loss
- or corruption when these settings are used.
-
- </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
- Place the database cluster's data directory in a memory-backed
- file system (i.e. <acronym class="acronym">RAM</acronym> disk). This eliminates all
- database disk I/O, but limits data storage to the amount of
- available memory (and perhaps swap).
- </p></li><li class="listitem"><p>
- Turn off <a class="xref" href="runtime-config-wal.html#GUC-FSYNC">fsync</a>; there is no need to flush
- data to disk.
- </p></li><li class="listitem"><p>
- Turn off <a class="xref" href="runtime-config-wal.html#GUC-SYNCHRONOUS-COMMIT">synchronous_commit</a>; there might be no
- need to force <acronym class="acronym">WAL</acronym> writes to disk on every
- commit. This setting does risk transaction loss (though not data
- corruption) in case of a crash of the <span class="emphasis"><em>database</em></span>.
- </p></li><li class="listitem"><p>
- Turn off <a class="xref" href="runtime-config-wal.html#GUC-FULL-PAGE-WRITES">full_page_writes</a>; there is no need
- to guard against partial page writes.
- </p></li><li class="listitem"><p>
- Increase <a class="xref" href="runtime-config-wal.html#GUC-MAX-WAL-SIZE">max_wal_size</a> and <a class="xref" href="runtime-config-wal.html#GUC-CHECKPOINT-TIMEOUT">checkpoint_timeout</a>; this reduces the frequency
- of checkpoints, but increases the storage requirements of
- <code class="filename">/pg_wal</code>.
- </p></li><li class="listitem"><p>
- Create <a class="link" href="sql-createtable.html#SQL-CREATETABLE-UNLOGGED">unlogged
- tables</a> to avoid <acronym class="acronym">WAL</acronym> writes, though it
- makes the tables non-crash-safe.
- </p></li></ul></div><p>
- </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="populate.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="performance-tips.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="parallel-query.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">14.4. Populating a Database </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 15. Parallel Query</td></tr></table></div></body></html>
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