<literal>sha256('abc'::bytea)</literal>
        <returnvalue>\xba7816bf8f01cfea414140de5dae2223&zwsp;b00361a396177a9cb410ff61f20015ad</returnvalue>
       </para></entry>
      </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <indexterm>
         <primary>sha384</primary>
        </indexterm>
        <function>sha384</function> ( <type>bytea</type> )
        <returnvalue>bytea</returnvalue>
       </para>
       <para>
        Computes the SHA-384 <link linkend="functions-hash-note">hash</link>
        of the binary string.
       </para>
       <para>
        <literal>sha384('abc'::bytea)</literal>
        <returnvalue>\xcb00753f45a35e8bb5a03d699ac65007&zwsp;272c32ab0eded1631a8b605a43ff5bed&zwsp;8086072ba1e7cc2358baeca134c825a7</returnvalue>
       </para></entry>
      </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <indexterm>
         <primary>sha512</primary>
        </indexterm>
        <function>sha512</function> ( <type>bytea</type> )
        <returnvalue>bytea</returnvalue>
       </para>
       <para>
        Computes the SHA-512 <link linkend="functions-hash-note">hash</link>
        of the binary string.
       </para>
       <para>
        <literal>sha512('abc'::bytea)</literal>
        <returnvalue>\xddaf35a193617abacc417349ae204131&zwsp;12e6fa4e89a97ea20a9eeee64b55d39a&zwsp;2192992a274fc1a836ba3c23a3feebbd&zwsp;454d4423643ce80e2a9ac94fa54ca49f</returnvalue>
       </para></entry>
      </row>

      <row>
       <entry role="func_table_entry"><para role="func_signature">
        <indexterm>
         <primary>substr</primary>
        </indexterm>
        <function>substr</function> ( <parameter>bytes</parameter> <type>bytea</type>, <parameter>start</parameter> <type>integer</type> <optional>, <parameter>count</parameter> <type>integer</type> </optional> )
        <returnvalue>bytea</returnvalue>
       </para>
       <para>
        Extracts the substring of <parameter>bytes</parameter> starting at
        the <parameter>start</parameter>'th byte,
        and extending for <parameter>count</parameter> bytes if that is
        specified.  (Same
        as <literal>substring(<parameter>bytes</parameter>
        from <parameter>start</parameter>
        for <parameter>count</parameter>)</literal>.)
       </para>
       <para>
        <literal>substr('\x1234567890'::bytea, 3, 2)</literal>
        <returnvalue>\x5678</returnvalue>
       </para></entry>
      </row>
    </tbody>
   </tgroup>
  </table>

  <para id="functions-zerobased-note">
   Functions <function>get_byte</function> and <function>set_byte</function>
   number the first byte of a binary string as byte 0.
   Functions <function>get_bit</function> and <function>set_bit</function>
   number bits from the right within each byte; for example bit 0 is the least
   significant bit of the first byte, and bit 15 is the most significant bit
   of the second byte.
  </para>

  <para id="functions-hash-note">
   For historical reasons, the function <function>md5</function>
   returns a hex-encoded value of type <type>text</type> whereas the SHA-2
   functions return type <type>bytea</type>.  Use the functions
   <link linkend="function-encode"><function>encode</function></link>
   and <link linkend="function-decode"><function>decode</function></link> to
   convert between the two.  For example write <literal>encode(sha256('abc'),
   'hex')</literal> to get a hex-encoded text representation,
   or <literal>decode(md5('abc'), 'hex')</literal> to get
   a <type>bytea</type> value.
  </para>

  <para>
   <indexterm>
    <primary>character string</primary>
    <secondary>converting to binary string</secondary>
   </indexterm>
   <indexterm>
    <primary>binary string</primary>
    <secondary>converting to character string</secondary>
   </indexterm>
   Functions for converting strings between different character sets
   (encodings), and for representing arbitrary binary data in