diff options
Diffstat (limited to 'doc/src/sgml/html/sql-set.html')
| -rw-r--r-- | doc/src/sgml/html/sql-set.html | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/doc/src/sgml/html/sql-set.html b/doc/src/sgml/html/sql-set.html new file mode 100644 index 0000000..4b8945f --- /dev/null +++ b/doc/src/sgml/html/sql-set.html @@ -0,0 +1,153 @@ +<?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>SET</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-selectinto.html" title="SELECT INTO" /><link rel="next" href="sql-set-constraints.html" title="SET CONSTRAINTS" /></head><body id="docContent" class="container-fluid col-10"><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">SET</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-selectinto.html" title="SELECT INTO">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 13.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="sql-set-constraints.html" title="SET CONSTRAINTS">Next</a></td></tr></table><hr></hr></div><div class="refentry" id="SQL-SET"><div class="titlepage"></div><a id="id-1.9.3.173.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">SET</span></h2><p>SET — change a run-time parameter</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis"> +SET [ SESSION | LOCAL ] <em class="replaceable"><code>configuration_parameter</code></em> { TO | = } { <em class="replaceable"><code>value</code></em> | '<em class="replaceable"><code>value</code></em>' | DEFAULT } +SET [ SESSION | LOCAL ] TIME ZONE { <em class="replaceable"><code>timezone</code></em> | LOCAL | DEFAULT } +</pre></div><div class="refsect1" id="id-1.9.3.173.5"><h2>Description</h2><p> + The <code class="command">SET</code> command changes run-time configuration + parameters. Many of the run-time parameters listed in + <a class="xref" href="runtime-config.html" title="Chapter 19. Server Configuration">Chapter 19</a> can be changed on-the-fly with + <code class="command">SET</code>. + (But some require superuser privileges to change, and others cannot + be changed after server or session start.) + <code class="command">SET</code> only affects the value used by the current + session. + </p><p> + If <code class="command">SET</code> (or equivalently <code class="command">SET SESSION</code>) + is issued within a transaction that is later aborted, the effects of the + <code class="command">SET</code> command disappear when the transaction is rolled + back. Once the surrounding transaction is committed, the effects + will persist until the end of the session, unless overridden by another + <code class="command">SET</code>. + </p><p> + The effects of <code class="command">SET LOCAL</code> last only till the end of + the current transaction, whether committed or not. A special case is + <code class="command">SET</code> followed by <code class="command">SET LOCAL</code> within + a single transaction: the <code class="command">SET LOCAL</code> value will be + seen until the end of the transaction, but afterwards (if the transaction + is committed) the <code class="command">SET</code> value will take effect. + </p><p> + The effects of <code class="command">SET</code> or <code class="command">SET LOCAL</code> are + also canceled by rolling back to a savepoint that is earlier than the + command. + </p><p> + If <code class="command">SET LOCAL</code> is used within a function that has a + <code class="literal">SET</code> option for the same variable (see + <a class="xref" href="sql-createfunction.html" title="CREATE FUNCTION"><span class="refentrytitle">CREATE FUNCTION</span></a>), + the effects of the <code class="command">SET LOCAL</code> command disappear at + function exit; that is, the value in effect when the function was called is + restored anyway. This allows <code class="command">SET LOCAL</code> to be used for + dynamic or repeated changes of a parameter within a function, while still + having the convenience of using the <code class="literal">SET</code> option to save and + restore the caller's value. However, a regular <code class="command">SET</code> command + overrides any surrounding function's <code class="literal">SET</code> option; its effects + will persist unless rolled back. + </p><div class="note"><h3 class="title">Note</h3><p> + In <span class="productname">PostgreSQL</span> versions 8.0 through 8.2, + the effects of a <code class="command">SET LOCAL</code> would be canceled by + releasing an earlier savepoint, or by successful exit from a + <span class="application">PL/pgSQL</span> exception block. This behavior + has been changed because it was deemed unintuitive. + </p></div></div><div class="refsect1" id="id-1.9.3.173.6"><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">SESSION</code></span></dt><dd><p> + Specifies that the command takes effect for the current session. + (This is the default if neither <code class="literal">SESSION</code> nor + <code class="literal">LOCAL</code> appears.) + </p></dd><dt><span class="term"><code class="literal">LOCAL</code></span></dt><dd><p> + Specifies that the command takes effect for only the current + transaction. After <code class="command">COMMIT</code> or <code class="command">ROLLBACK</code>, + the session-level setting takes effect again. Issuing this + outside of a transaction block emits a warning and otherwise has + no effect. + </p></dd><dt><span class="term"><em class="replaceable"><code>configuration_parameter</code></em></span></dt><dd><p> + Name of a settable run-time parameter. Available parameters are + documented in <a class="xref" href="runtime-config.html" title="Chapter 19. Server Configuration">Chapter 19</a> and below. + </p></dd><dt><span class="term"><em class="replaceable"><code>value</code></em></span></dt><dd><p> + New value of parameter. Values can be specified as string + constants, identifiers, numbers, or comma-separated lists of + these, as appropriate for the particular parameter. + <code class="literal">DEFAULT</code> can be written to specify + resetting the parameter to its default value (that is, whatever + value it would have had if no <code class="command">SET</code> had been executed + in the current session). + </p></dd></dl></div><p> + Besides the configuration parameters documented in <a class="xref" href="runtime-config.html" title="Chapter 19. Server Configuration">Chapter 19</a>, there are a few that can only be + adjusted using the <code class="command">SET</code> command or that have a + special syntax: + + </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">SCHEMA</code></span></dt><dd><p><code class="literal">SET SCHEMA '<em class="replaceable"><code>value</code></em>'</code> is an alias for + <code class="literal">SET search_path TO <em class="replaceable"><code>value</code></em></code>. Only one + schema can be specified using this syntax. + </p></dd><dt><span class="term"><code class="literal">NAMES</code></span></dt><dd><p><code class="literal">SET NAMES <em class="replaceable"><code>value</code></em></code> is an alias for + <code class="literal">SET client_encoding TO <em class="replaceable"><code>value</code></em></code>. + </p></dd><dt><span class="term"><code class="literal">SEED</code></span></dt><dd><p> + Sets the internal seed for the random number generator (the + function <code class="function">random</code>). Allowed values are + floating-point numbers between -1 and 1, which are then + multiplied by 2<sup>31</sup>-1. + </p><p> + The seed can also be set by invoking the function + <code class="function">setseed</code>: +</p><pre class="programlisting"> +SELECT setseed(<em class="replaceable"><code>value</code></em>); +</pre></dd><dt><span class="term"><code class="literal">TIME ZONE</code></span></dt><dd><p><code class="literal">SET TIME ZONE <em class="replaceable"><code>value</code></em></code> is an alias + for <code class="literal">SET timezone TO <em class="replaceable"><code>value</code></em></code>. The + syntax <code class="literal">SET TIME ZONE</code> allows special syntax + for the time zone specification. Here are examples of valid + values: + + </p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><code class="literal">'PST8PDT'</code></span></dt><dd><p> + The time zone for Berkeley, California. + </p></dd><dt><span class="term"><code class="literal">'Europe/Rome'</code></span></dt><dd><p> + The time zone for Italy. + </p></dd><dt><span class="term"><code class="literal">-7</code></span></dt><dd><p> + The time zone 7 hours west from UTC (equivalent + to PDT). Positive values are east from UTC. + </p></dd><dt><span class="term"><code class="literal">INTERVAL '-08:00' HOUR TO MINUTE</code></span></dt><dd><p> + The time zone 8 hours west from UTC (equivalent + to PST). + </p></dd><dt><span class="term"><code class="literal">LOCAL</code><br /></span><span class="term"><code class="literal">DEFAULT</code></span></dt><dd><p> + Set the time zone to your local time zone (that is, the + server's default value of <code class="varname">timezone</code>). + </p></dd></dl></div><p> + </p><p> + Timezone settings given as numbers or intervals are internally + translated to POSIX timezone syntax. For example, after + <code class="literal">SET TIME ZONE -7</code>, <code class="command">SHOW TIME ZONE</code> would + report <code class="literal"><-07>+07</code>. + </p><p> + See <a class="xref" href="datatype-datetime.html#DATATYPE-TIMEZONES" title="8.5.3. Time Zones">Section 8.5.3</a> for more information + about time zones. + </p></dd></dl></div><p> + </p></div><div class="refsect1" id="id-1.9.3.173.7"><h2>Notes</h2><p> + The function <code class="function">set_config</code> provides equivalent + functionality; see <a class="xref" href="functions-admin.html#FUNCTIONS-ADMIN-SET" title="9.27.1. Configuration Settings Functions">Section 9.27.1</a>. + Also, it is possible to UPDATE the + <a class="link" href="view-pg-settings.html" title="51.85. pg_settings"><code class="structname">pg_settings</code></a> + system view to perform the equivalent of <code class="command">SET</code>. + </p></div><div class="refsect1" id="id-1.9.3.173.8"><h2>Examples</h2><p> + Set the schema search path: +</p><pre class="programlisting"> +SET search_path TO my_schema, public; +</pre><p> + </p><p> + Set the style of date to traditional + <span class="productname">POSTGRES</span> with <span class="quote">“<span class="quote">day before month</span>”</span> + input convention: +</p><pre class="screen"> +SET datestyle TO postgres, dmy; +</pre><p> + </p><p> + Set the time zone for Berkeley, California: +</p><pre class="screen"> +SET TIME ZONE 'PST8PDT'; +</pre><p> + </p><p> + Set the time zone for Italy: +</p><pre class="screen"> +SET TIME ZONE 'Europe/Rome'; +</pre></div><div class="refsect1" id="id-1.9.3.173.9"><h2>Compatibility</h2><p> + <code class="literal">SET TIME ZONE</code> extends syntax defined in the SQL + standard. The standard allows only numeric time zone offsets while + <span class="productname">PostgreSQL</span> allows more flexible + time-zone specifications. All other <code class="literal">SET</code> + features are <span class="productname">PostgreSQL</span> extensions. + </p></div><div class="refsect1" id="id-1.9.3.173.10"><h2>See Also</h2><span class="simplelist"><a class="xref" href="sql-reset.html" title="RESET"><span class="refentrytitle">RESET</span></a>, <a class="xref" href="sql-show.html" title="SHOW"><span class="refentrytitle">SHOW</span></a></span></div></div><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navfooter"><hr></hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="sql-selectinto.html" title="SELECT INTO">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="sql-set-constraints.html" title="SET CONSTRAINTS">Next</a></td></tr><tr><td width="40%" align="left" valign="top">SELECT INTO </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 13.4 Documentation">Home</a></td><td width="40%" align="right" valign="top"> SET CONSTRAINTS</td></tr></table></div></body></html>
\ No newline at end of file |