1<!--
2doc/src/sgml/ref/create_access_method.sgml
3PostgreSQL documentation
4-->
5
6<refentry id="sql-create-access-method">
7 <indexterm zone="sql-create-access-method">
8  <primary>CREATE ACCESS METHOD</primary>
9 </indexterm>
10
11 <refmeta>
12  <refentrytitle>CREATE ACCESS METHOD</refentrytitle>
13  <manvolnum>7</manvolnum>
14  <refmiscinfo>SQL - Language Statements</refmiscinfo>
15 </refmeta>
16
17 <refnamediv>
18  <refname>CREATE ACCESS METHOD</refname>
19  <refpurpose>define a new access method</refpurpose>
20 </refnamediv>
21
22 <refsynopsisdiv>
23<synopsis>
24CREATE ACCESS METHOD <replaceable class="parameter">name</replaceable>
25    TYPE <replaceable class="parameter">access_method_type</replaceable>
26    HANDLER <replaceable class="parameter">handler_function</replaceable>
27</synopsis>
28 </refsynopsisdiv>
29
30 <refsect1>
31  <title>Description</title>
32
33  <para>
34   <command>CREATE ACCESS METHOD</command> creates a new access method.
35  </para>
36
37  <para>
38   The access method name must be unique within the database.
39  </para>
40
41  <para>
42   Only superusers can define new access methods.
43  </para>
44 </refsect1>
45
46 <refsect1>
47  <title>Parameters</title>
48
49  <variablelist>
50   <varlistentry>
51    <term><replaceable class="parameter">name</replaceable></term>
52    <listitem>
53     <para>
54      The name of the access method to be created.
55     </para>
56    </listitem>
57   </varlistentry>
58
59   <varlistentry>
60    <term><replaceable class="parameter">access_method_type</replaceable></term>
61    <listitem>
62     <para>
63      This clause specifies the type of access method to define.
64      Only <literal>TABLE</literal> and <literal>INDEX</literal>
65      are supported at present.
66     </para>
67    </listitem>
68   </varlistentry>
69
70   <varlistentry>
71    <term><replaceable class="parameter">handler_function</replaceable></term>
72    <listitem>
73     <para>
74      <replaceable class="parameter">handler_function</replaceable> is the
75      name (possibly schema-qualified) of a previously registered function
76      that represents the access method.  The handler function must be
77      declared to take a single argument of type <type>internal</type>,
78      and its return type depends on the type of access method;
79      for <literal>TABLE</literal> access methods, it must
80      be <type>table_am_handler</type> and for <literal>INDEX</literal>
81      access methods, it must be <type>index_am_handler</type>.
82      The C-level API that the handler function must implement varies
83      depending on the type of access method. The table access method API
84      is described in <xref linkend="tableam"/> and the index access method
85      API is described in <xref linkend="indexam"/>.
86     </para>
87    </listitem>
88   </varlistentry>
89  </variablelist>
90 </refsect1>
91
92 <refsect1>
93  <title>Examples</title>
94
95  <para>
96   Create an index access method <literal>heptree</literal> with
97   handler function <literal>heptree_handler</literal>:
98<programlisting>
99CREATE ACCESS METHOD heptree TYPE INDEX HANDLER heptree_handler;
100</programlisting></para>
101 </refsect1>
102
103 <refsect1>
104  <title>Compatibility</title>
105
106  <para>
107   <command>CREATE ACCESS METHOD</command> is a
108   <productname>PostgreSQL</productname> extension.
109  </para>
110 </refsect1>
111
112 <refsect1>
113  <title>See Also</title>
114
115  <simplelist type="inline">
116   <member><xref linkend="sql-drop-access-method"/></member>
117   <member><xref linkend="sql-createopclass"/></member>
118   <member><xref linkend="sql-createopfamily"/></member>
119  </simplelist>
120 </refsect1>
121
122</refentry>
123