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<!--
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>
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