pg-parameter-status.xml

<?xml version="1.0" encoding="utf-8"?>
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<refentry xml:id="function.pg-parameter-status" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>pg_parameter_status</refname>
  <refpurpose>Looks up a current parameter setting of the server</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>string</type><methodname>pg_parameter_status</methodname>
   <methodparam choice="opt"><type>PgSql\Connection</type><parameter>connection</parameter></methodparam>
   <methodparam><type>string</type><parameter>param_name</parameter></methodparam>
  </methodsynopsis>
  <para>
    Looks up a current parameter setting of the server.
  </para>
  <para>
    Certain parameter values are reported by the server automatically at 
    connection startup or whenever their values change. <function>pg_parameter_status</function> can be 
    used to interrogate these settings. It returns the current value of a 
    parameter if known, or &false; if the parameter is not known.
  </para>
  <para>
    Parameters reported as of PostgreSQL 8.0 include <literal>server_version</literal>, 
    <literal>server_encoding</literal>, <literal>client_encoding</literal>, 
    <literal>is_superuser</literal>, <literal>session_authorization</literal>, 
    <literal>DateStyle</literal>, <literal>TimeZone</literal>, and <literal>integer_datetimes</literal>.
    (<literal>server_encoding</literal>, <literal>TimeZone</literal>, and 
    <literal>integer_datetimes</literal> were not reported by releases before 8.0.) Note that 
    <literal>server_version</literal>, <literal>server_encoding</literal> and <literal>integer_datetimes</literal> 
    cannot change after PostgreSQL startup.
  </para>
  <para>
    PostgreSQL 7.3 or lower servers do not report parameter settings,
    <function>pg_parameter_status</function>
    includes logic to obtain values for <literal>server_version</literal> and 
    <literal>client_encoding</literal>
    anyway. Applications are encouraged to use <function>pg_parameter_status</function> rather than ad 
    hoc code to determine these values.
  </para>
  <caution>
    <para>
      On a pre-7.4
      PostgreSQL server, changing <literal>client_encoding</literal> via <literal>SET</literal> after connection startup will 
      not be reflected by <function>pg_parameter_status</function>.
     </para>
  </caution>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>connection</parameter></term>
     <listitem>
      &pgsql.parameter.connection-with-unspecified-default;
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>param_name</parameter></term>
     <listitem>
        <para>
         Possible <parameter>param_name</parameter> values include <literal>server_version</literal>, 
        <literal>server_encoding</literal>, <literal>client_encoding</literal>, 
        <literal>is_superuser</literal>, <literal>session_authorization</literal>, 
        <literal>DateStyle</literal>, <literal>TimeZone</literal>, and 
        <literal>integer_datetimes</literal>.  Note that this value is case-sensitive.
        </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>A <type>string</type> containing the value of the parameter, &false; on failure or invalid
  <parameter>param_name</parameter>.</para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <informaltable>
   <tgroup cols="2">
    <thead>
     <row>
      <entry>&Version;</entry>
      <entry>&Description;</entry>
     </row>
    </thead>
    <tbody>
     &pgsql.changelog.connection-object;
    </tbody>
   </tgroup>
  </informaltable>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>pg_parameter_status</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
  $dbconn = pg_connect("dbname=publisher") or die("Could not connect");

  echo "Server encoding: ", pg_parameter_status($dbconn, "server_encoding");
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
Server encoding: SQL_ASCII
]]>
    </screen>
   </example>
  </para>
 </refsect1>
</refentry>

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