pg-trace.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<!-- splitted from ./en/functions/pgsql.xml, last change in rev 1.7 -->
<refentry xml:id="function.pg-trace" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>pg_trace</refname>
  <refpurpose>Enable tracing a PostgreSQL connection</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>bool</type><methodname>pg_trace</methodname>
   <methodparam><type>string</type><parameter>filename</parameter></methodparam>
   <methodparam choice="opt"><type>string</type><parameter>mode</parameter><initializer>"w"</initializer></methodparam>
   <methodparam choice="opt"><type class="union"><type>PgSql\Connection</type><type>null</type></type><parameter>connection</parameter><initializer>&null;</initializer></methodparam>
   <methodparam choice="opt"><type>int</type><parameter>trace_mode</parameter><initializer>0</initializer></methodparam>
  </methodsynopsis>
  <para>
   <function>pg_trace</function> enables tracing of the PostgreSQL
   frontend/backend communication to a file. To fully understand the results,
   one needs to be familiar with the internals of PostgreSQL
   communication protocol.
  </para>
  <para>For those who are not, it can still be
   useful for tracing errors in queries sent to the server, you
   could do for example <command>grep '^To backend'
   trace.log</command> and see what queries actually were sent to the
   PostgreSQL server. For more information, refer to the
   <link xlink:href="&url.pgsql.manual;">PostgreSQL Documentation</link>.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>filename</parameter></term>
     <listitem>
      <para>
       The full path and file name of the file in which to write the
       trace log.  Same as in <function>fopen</function>.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>mode</parameter></term>
     <listitem>
      <para>
       An optional file access mode, same as for <function>fopen</function>.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>connection</parameter></term>
     <listitem>
      &pgsql.parameter.connection-with-nullable-default;
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>trace_mode</parameter></term>
     <listitem>
      <para>
       An optional trace mode with the following constants
       <constant>PGSQL_TRACE_SUPPRESS_TIMESTAMPS</constant> and
       <constant>PGSQL_TRACE_REGRESS_MODE</constant>
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   &return.success;
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <informaltable>
   <tgroup cols="2">
    <thead>
     <row>
      <entry>&Version;</entry>
      <entry>&Description;</entry>
     </row>
    </thead>
    <tbody>
     <row>
      <entry>8.3.0</entry>
      <entry>
       <parameter>trace_mode</parameter> has been added.
      </entry>
     </row>
     &pgsql.changelog.connection-object;
     <row>
      <entry>8.0.0</entry>
      <entry>
       <parameter>connection</parameter> is now nullable.
      </entry>
     </row>
    </tbody>
   </tgroup>
  </informaltable>
 </refsect1>
 
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>pg_trace</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
$pgsql_conn = pg_connect("dbname=mark host=localhost");

if ($pgsql_conn) {
   pg_trace('/tmp/trace.log', 'w', $pgsql_conn);
   pg_query("SELECT 1");
   pg_untrace($pgsql_conn);
   // Now /tmp/trace.log will contain backend communication
} else {
   print pg_last_error($pgsql_conn);
   exit;
}
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>
 
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>fopen</function></member>
    <member><function>pg_untrace</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>
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