doc/src/sgml/ref/create_access_method.sgml - master - githubmirror/postgres

doc/src/sgml/ref/create_access_method.sgml
122 строки3 KB
Andres Freund
tableam: basic documentation.
04 апр 2019, 03:40
04 апр 2019, 03:40b73c3a1
<!--
doc/src/sgml/ref/create_access_method.sgml
PostgreSQL documentation
-->

<refentry id="sql-create-access-method">
 <indexterm zone="sql-create-access-method">
  <primary>CREATE ACCESS METHOD</primary>
 </indexterm>

 <refmeta>
  <refentrytitle>CREATE ACCESS METHOD</refentrytitle>
  <manvolnum>7</manvolnum>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>CREATE ACCESS METHOD</refname>
  <refpurpose>define a new access method</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
CREATE ACCESS METHOD <replaceable class="parameter">name</replaceable>
    TYPE <replaceable class="parameter">access_method_type</replaceable>
    HANDLER <replaceable class="parameter">handler_function</replaceable>
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>CREATE ACCESS METHOD</command> creates a new access method.
  </para>

  <para>
   The access method name must be unique within the database.
  </para>

  <para>
   Only superusers can define new access methods.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

  <variablelist>
   <varlistentry>
    <term><replaceable class="parameter">name</replaceable></term>
    <listitem>
     <para>
      The name of the access method to be created.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">access_method_type</replaceable></term>
    <listitem>
     <para>
      This clause specifies the type of access method to define.
      Only <literal>TABLE</literal> and <literal>INDEX</literal>
      are supported at present.
     </para>
    </listitem>
   </varlistentry>

   <varlistentry>
    <term><replaceable class="parameter">handler_function</replaceable></term>
    <listitem>
     <para>
      <replaceable class="parameter">handler_function</replaceable> is the
      name (possibly schema-qualified) of a previously registered function
      that represents the access method.  The handler function must be
      declared to take a single argument of type <type>internal</type>,
      and its return type depends on the type of access method;
      for <literal>TABLE</literal> access methods, it must
      be <type>table_am_handler</type> and for <literal>INDEX</literal>
      access methods, it must be <type>index_am_handler</type>.
      The C-level API that the handler function must implement varies
      depending on the type of access method. The table access method API
      is described in <xref linkend="tableam"/> and the index access method
      API is described in <xref linkend="indexam"/>.
     </para>
    </listitem>
   </varlistentry>
  </variablelist>
 </refsect1>

 <refsect1>
  <title>Examples</title>

  <para>
   Create an index access method <literal>heptree</literal> with
   handler function <literal>heptree_handler</literal>:
<programlisting>
CREATE ACCESS METHOD heptree TYPE INDEX HANDLER heptree_handler;
</programlisting></para>
 </refsect1>

 <refsect1>
  <title>Compatibility</title>

  <para>
   <command>CREATE ACCESS METHOD</command> is a
   <productname>PostgreSQL</productname> extension.
  </para>
 </refsect1>

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

  <simplelist type="inline">
   <member><xref linkend="sql-drop-access-method"/></member>
   <member><xref linkend="sql-createopclass"/></member>
   <member><xref linkend="sql-createopfamily"/></member>
  </simplelist>
 </refsect1>

</refentry>