drop_opclass.sgml

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

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$PostgreSQL: pgsql/doc/src/sgml/ref/drop_opclass.sgml,v 1.8 2003/11/29 19:51:38 pgsql Exp $
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<refentry id="SQL-DROPOPCLASS">
 <refmeta>
  <refentrytitle id="SQL-DROPOPCLASS-TITLE">DROP OPERATOR CLASS</refentrytitle>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>DROP OPERATOR CLASS</refname>
  <refpurpose>remove an operator class</refpurpose>
 </refnamediv>
  
 <indexterm zone="sql-dropopclass">
  <primary>DROP OPERATOR CLASS</primary>
 </indexterm>

 <refsynopsisdiv>
<synopsis>
DROP OPERATOR CLASS <replaceable class="PARAMETER">name</replaceable> USING <replaceable class="PARAMETER">index_method</replaceable> [ CASCADE | RESTRICT ]
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>DROP OPERATOR CLASS</command> drops an existing operator class.
   To execute this command you must be the owner of the operator class.
  </para>
 </refsect1>
  
 <refsect1>
  <title>Parameters</title>

  <variablelist>
   <varlistentry>
    <term><replaceable class="parameter">name</replaceable></term>
    <listitem>
     <para>
      The name (optionally schema-qualified) of an existing operator class.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">index_method</replaceable></term>
    <listitem>
     <para>
      The name of the index access method the operator class is for.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>CASCADE</literal></term>
    <listitem>
     <para>
      Automatically drop objects that depend on the operator class.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><literal>RESTRICT</literal></term>
    <listitem>
     <para>
      Refuse to drop the operator class if any objects depend on it.
      This is the default.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1>
  <title>Examples</title>

  <para>
   Remove the B-tree operator class <literal>widget_ops</literal>:

<programlisting>
DROP OPERATOR CLASS widget_ops USING btree;
</programlisting>

   This command will not succeed if there are any existing indexes
   that use the operator class.  Add <literal>CASCADE</> to drop
   such indexes along with the operator class.
  </para>
 </refsect1>
 
 <refsect1>
  <title>Compatibility</title>

  <para>
   There is no <command>DROP OPERATOR CLASS</command> statement in the
   SQL standard.
  </para>
 </refsect1>

 <refsect1>
  <title>See Also</title>

  <simplelist type="inline">
   <member><xref linkend="sql-alteropclass" endterm="sql-alteropclass-title"></member>
   <member><xref linkend="sql-createopclass" endterm="sql-createopclass-title"></member>
  </simplelist>
 </refsect1>

</refentry>

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