oci-set-prefetch-lob.xml

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<refentry xmlns="http://docbook.org/ns/docbook" xml:id="function.oci-set-prefetch-lob">
 <refnamediv>
  <refname>oci_set_prefetch_lob</refname>
  <refpurpose>Sets the amount of data prefetched for each CLOB or BLOB.</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>bool</type><methodname>oci_set_prefetch_lob</methodname>
   <methodparam><type>resource</type><parameter>statement</parameter></methodparam>
   <methodparam><type>int</type><parameter>prefetch_lob_size</parameter></methodparam>
  </methodsynopsis>
  <para>
   Sets the internal buffer size used to fetch each CLOB or BLOB value when the
   implementation gets the internal Oracle LOB locator from the database after
   a successful query call to <function>oci_execute</function> and for each
   subsequent internal fetch request to the database.  Increasing this value
   can improve the performance of fetching smaller LOBs by reducing round-trips
   between PHP and the database.  Memory usage will change.
  </para>
  <para>
   The value affects LOBs returned as OCILob instances and also those returned
   using <constant>OCI_RETURN_LOBS</constant>.
  </para>
  <para>
   Call <function>oci_set_prefetch_lob</function> before
   calling <function>oci_execute</function>.  If it is not called, the value
   of <link linkend="ini.oci8.prefetch-lob-size">oci8.prefetch_lob_size</link>
   is used.
  </para>
  <para>
   The LOB prefetch value should only be set with Oracle Database 12.2 or later.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>statement</parameter></term>
     <listitem>
       &oci.arg.statement.id;
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>prefetch_lob_size</parameter></term>
     <listitem>
      <para>
       The number of bytes of each LOB to be prefetched, &gt;= 0
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

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

 <refsect1 role="changelog">
  &reftitle.changelog;
  <para>
   <informaltable>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>&Version;</entry>
       <entry>&Description;</entry>
      </row>
     </thead>
     <tbody>
      <row>
       <entry>PECL OCI8 3.2</entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title>Changing the LOB prefetch value for a query</title>
    <programlisting role="php">
<![CDATA[
<?php

$conn = oci_connect('hr', 'welcome', 'localhost/XE');

$stid = oci_parse($conn, 'SELECT myclob FROM mytable');
oci_set_prefetch_lob($stid, 100000);  // Set before calling oci_execute()
oci_execute($stid);

echo "<table border='1'>\n";
while ($row = oci_fetch_array($stid, OCI_ASSOC+OCI_RETURN_NULLS+OCI_RETURN_LOBS)) {
    echo "<tr>\n";
    foreach ($row as $item) {
        echo "    <td>".($item !== null ? htmlentities($item, ENT_QUOTES) : "&nbsp;")."</td>\n";
    }
    echo "</tr>\n";
}
echo "</table>\n";

oci_free_statement($stid);
oci_close($conn);

?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member>
     <link linkend="ini.oci8.prefetch-lob-size">oci8.prefetch_lob_size</link>
     ini option
    </member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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