(<structfield>indnkeyatts</structfield> values), this contains the OID
       of the collation to use for the index, or zero if the column is not of
       a collatable data type.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>indclass</structfield> <type>oidvector</type>
       (references <link linkend="catalog-pg-opclass"><structname>pg_opclass</structname></link>.<structfield>oid</structfield>)
      </para>
      <para>
       For each column in the index key
       (<structfield>indnkeyatts</structfield> values), this contains the OID
       of the operator class to use.  See
       <link linkend="catalog-pg-opclass"><structname>pg_opclass</structname></link> for details.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>indoption</structfield> <type>int2vector</type>
      </para>
      <para>
       This is an array of <structfield>indnkeyatts</structfield> values that
       store per-column flag bits.  The meaning of the bits is defined by
       the index's access method.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>indexprs</structfield> <type>pg_node_tree</type>
      </para>
      <para>
       Expression trees (in <function>nodeToString()</function>
       representation) for index attributes that are not simple column
       references.  This is a list with one element for each zero
       entry in <structfield>indkey</structfield>.  Null if all index attributes
       are simple references.
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>indpred</structfield> <type>pg_node_tree</type>
      </para>
      <para>
       Expression tree (in <function>nodeToString()</function>
       representation) for partial index predicate.  Null if not a
       partial index.
      </para></entry>
     </row>
    </tbody>
   </tgroup>
  </table>

 </sect1>


 <sect1 id="catalog-pg-inherits">
  <title><structname>pg_inherits</structname></title>

  <indexterm zone="catalog-pg-inherits">
   <primary>pg_inherits</primary>
  </indexterm>

  <para>
   The catalog <structname>pg_inherits</structname> records information about
   table and index inheritance hierarchies.  There is one entry for each direct
   parent-child table or index relationship in the database.  (Indirect
   inheritance can be determined by following chains of entries.)
  </para>

  <table>
   <title><structname>pg_inherits</structname> Columns</title>
   <tgroup cols="1">
    <thead>
     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       Column Type
      </para>
      <para>
       Description
      </para></entry>
     </row>
    </thead>

    <tbody>
     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>inhrelid</structfield> <type>oid</type>
       (references <link linkend="catalog-pg-class"><structname>pg_class</structname></link>.<structfield>oid</structfield>)
      </para>
      <para>
       The OID of the child table or index
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>inhparent</structfield> <type>oid</type>
       (references <link linkend="catalog-pg-class"><structname>pg_class</structname></link>.<structfield>oid</structfield>)
      </para>
      <para>
       The OID of the parent table or index
      </para></entry>
     </row>

     <row>
      <entry role="catalog_table_entry"><para role="column_definition">
       <structfield>inhseqno</structfield> <type>int4</type>
      </para>
      <para>
       If there is more than one direct parent for a child table (multiple
       inheritance), this number tells the order