pg-lo-seek.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<!-- splitted from ./en/functions/pgsql.xml, last change in rev 1.2 -->
<refentry xml:id="function.pg-lo-seek" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>pg_lo_seek</refname>
  <refpurpose>
   Seeks position within a large object
  </refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>bool</type><methodname>pg_lo_seek</methodname>
   <methodparam><type>PgSql\Lob</type><parameter>lob</parameter></methodparam>
   <methodparam><type>int</type><parameter>offset</parameter></methodparam>
   <methodparam choice="opt"><type>int</type><parameter>whence</parameter><initializer><constant>SEEK_CUR</constant></initializer></methodparam>
  </methodsynopsis>
  <para>
   <function>pg_lo_seek</function> seeks a position within an <classname>PgSql\Lob</classname> instance.
  </para>
  <para>
   To use the large object interface, it is necessary to
   enclose it within a transaction block.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>lob</parameter></term>
     <listitem>
      &pgsql.parameter.lob;
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>offset</parameter></term>
     <listitem>
      <para>
       The number of bytes to seek.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>whence</parameter></term>
     <listitem>
      <para>
       One of the constants <constant>PGSQL_SEEK_SET</constant> (seek from object start), 
       <constant>PGSQL_SEEK_CUR</constant> (seek from current position)
       or <constant>PGSQL_SEEK_END</constant> (seek from object end) .
      </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>
     &pgsql.changelog.lob-object;
    </tbody>
   </tgroup>
  </informaltable>
 </refsect1>
 
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>pg_lo_seek</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
   $doc_oid = 189762345;
   $database = pg_connect("dbname=jacarta");
   pg_query($database, "begin");
   $handle = pg_lo_open($database, $doc_oid, "r");
   // Skip first 50000 bytes
   pg_lo_seek($handle, 50000, PGSQL_SEEK_SET);
   // Read the next 10000 bytes
   $data = pg_lo_read($handle, 10000);
   pg_query($database, "commit");
   echo $data;
?>
]]>
    </programlisting>
   </example> 
  </para>
 </refsect1>
 
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>pg_lo_tell</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>
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