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Green_GoodERP18_FSJ_Standard/PostgreSQL/doc/postgresql/html/sql-altersystem.html

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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>ALTER SYSTEM</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="sql-altersubscription.html" title="ALTER SUBSCRIPTION" /><link rel="next" href="sql-altertable.html" title="ALTER TABLE" /></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">ALTER SYSTEM</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-altersubscription.html" title="ALTER SUBSCRIPTION">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><th width="60%" align="center">SQL Commands</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="sql-altertable.html" title="ALTER TABLE">Next</a></td></tr></table><hr></hr></div><div class="refentry" id="SQL-ALTERSYSTEM"><div class="titlepage"></div><a id="id-1.9.3.34.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">ALTER SYSTEM</span></h2><p>ALTER SYSTEM — change a server configuration parameter</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">

  3. ALTER SYSTEM SET <em class="replaceable"><code>configuration_parameter</code></em> { TO | = } { <em class="replaceable"><code>value</code></em> | '<em class="replaceable"><code>value</code></em>' | DEFAULT }

  4. 

  5. ALTER SYSTEM RESET <em class="replaceable"><code>configuration_parameter</code></em>

  6. ALTER SYSTEM RESET ALL

  7. </pre></div><div class="refsect1" id="id-1.9.3.34.5"><h2>Description</h2><p>

  8.    <code class="command">ALTER SYSTEM</code> is used for changing server configuration

  9.    parameters across the entire database cluster.  It can be more convenient

  10.    than the traditional method of manually editing

  11.    the <code class="filename">postgresql.conf</code> file.

  12.    <code class="command">ALTER SYSTEM</code> writes the given parameter setting to

  13.    the <code class="filename">postgresql.auto.conf</code> file, which is read in

  14.    addition to <code class="filename">postgresql.conf</code>.

  15.    Setting a parameter to <code class="literal">DEFAULT</code>, or using the

  16.    <code class="command">RESET</code> variant, removes that configuration entry from the

  17.    <code class="filename">postgresql.auto.conf</code> file. Use <code class="literal">RESET

  18.    ALL</code> to remove all such configuration entries.

  19.   </p><p>

  20.    Values set with <code class="command">ALTER SYSTEM</code> will be effective after

  21.    the next server configuration reload, or after the next server restart

  22.    in the case of parameters that can only be changed at server start.

  23.    A server configuration reload can be commanded by calling the SQL

  24.    function <code class="function">pg_reload_conf()</code>, running <code class="literal">pg_ctl reload</code>,

  25.    or sending a <span class="systemitem">SIGHUP</span> signal to the main server process.

  26.   </p><p>

  27.    Only superusers can use <code class="command">ALTER SYSTEM</code>.  Also, since

  28.    this command acts directly on the file system and cannot be rolled back,

  29.    it is not allowed inside a transaction block or function.

  30.   </p></div><div class="refsect1" id="id-1.9.3.34.6"><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>configuration_parameter</code></em></span></dt><dd><p>

  31.       Name of a settable configuration parameter.  Available parameters are

  32.       documented in <a class="xref" href="runtime-config.html" title="Chapter 19. Server Configuration">Chapter 19</a>.

  33.      </p></dd><dt><span class="term"><em class="replaceable"><code>value</code></em></span></dt><dd><p>

  34.       New value of the parameter.  Values can be specified as string

  35.       constants, identifiers, numbers, or comma-separated lists of

  36.       these, as appropriate for the particular parameter.

  37.       <code class="literal">DEFAULT</code> can be written to specify removing the

  38.       parameter and its value from <code class="filename">postgresql.auto.conf</code>.

  39.      </p></dd></dl></div></div><div class="refsect1" id="id-1.9.3.34.7"><h2>Notes</h2><p>

  40.    This command can't be used to set <a class="xref" href="runtime-config-file-locations.html#GUC-DATA-DIRECTORY">data_directory</a>,

  41.    nor parameters that are not allowed in <code class="filename">postgresql.conf</code>

  42.    (e.g., <a class="link" href="runtime-config-preset.html" title="19.15. Preset Options">preset options</a>).

  43.   </p><p>

  44.    See <a class="xref" href="config-setting.html" title="19.1. Setting Parameters">Section 19.1</a> for other ways to set the parameters.

  45.   </p></div><div class="refsect1" id="id-1.9.3.34.8"><h2>Examples</h2><p>

  46.    Set the <code class="literal">wal_level</code>:

  47. </p><pre class="programlisting">

  48. ALTER SYSTEM SET wal_level = replica;

  49. </pre><p>

  50.   </p><p>

  51.    Undo that, restoring whatever setting was effective

  52.    in <code class="filename">postgresql.conf</code>:

  53. </p><pre class="programlisting">

  54. ALTER SYSTEM RESET wal_level;

  55. </pre></div><div class="refsect1" id="id-1.9.3.34.9"><h2>Compatibility</h2><p>

  56.    The <code class="command">ALTER SYSTEM</code> statement is a

  57.    <span class="productname">PostgreSQL</span> extension.

  58.   </p></div><div class="refsect1" id="id-1.9.3.34.10"><h2>See Also</h2><span class="simplelist"><a class="xref" href="sql-set.html" title="SET"><span class="refentrytitle">SET</span></a>, <a class="xref" href="sql-show.html" title="SHOW"><span class="refentrytitle">SHOW</span></a></span></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="sql-altersubscription.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sql-commands.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="sql-altertable.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">ALTER SUBSCRIPTION </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> ALTER TABLE</td></tr></table></div></body></html>
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