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Peter Eisentraut
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doc/src/sgml/ref/create_opclass.sgml
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<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_opclass.sgml,v 1.6 2003/03/25 16:15:39 petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_opclass.sgml,v 1.7 2003/04/22 10:08:08 petere Exp $
PostgreSQL documentation
-->
@@ -8,206 +8,44 @@ PostgreSQL documentation
<refentrytitle id="sql-createopclass-title">CREATE OPERATOR CLASS</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>
CREATE OPERATOR CLASS
</refname>
<refpurpose>
define a new operator class for indexes
</refpurpose>
</refnamediv>
<refname>CREATE OPERATOR CLASS</refname>
<refpurpose>define a new operator class for indexes</refpurpose>
</refnamediv>
<refsynopsisdiv>
<refsynopsisdivinfo>
<date>2002-07-28</date>
</refsynopsisdivinfo>
<synopsis>
CREATE OPERATOR CLASS <replaceable class="parameter">name</replaceable> [ DEFAULT ] FOR TYPE <replaceable class="parameter">data_type</replaceable> USING <replaceable class="parameter">access_method</replaceable> AS
{ OPERATOR <replaceable class="parameter">strategy_number</replaceable> <replaceable class="parameter">operator_id</replaceable> [ ( <replaceable class="parameter">type</replaceable>, <replaceable class="parameter">type</replaceable> ) ] [ RECHECK ]
| FUNCTION <replaceable class="parameter">support_number</replaceable> <replaceable class="parameter">func_name</replaceable> ( <replaceable class="parameter">parameter_types</replaceable> )
<synopsis>
CREATE OPERATOR CLASS <replaceable class="parameter">name</replaceable> [ DEFAULT ] FOR TYPE <replaceable class="parameter">data_type</replaceable> USING <replaceable class="parameter">index_method</replaceable> AS
{ OPERATOR <replaceable class="parameter">strategy_number</replaceable> <replaceable class="parameter">operator_name</replaceable> [ ( <replaceable class="parameter">op_type</replaceable>, <replaceable class="parameter">op_type</replaceable> ) ] [ RECHECK ]
| FUNCTION <replaceable class="parameter">support_number</replaceable> <replaceable class="parameter">func_name</replaceable> ( <replaceable class="parameter">argument_types</replaceable> )
| STORAGE <replaceable class="parameter">storage_type</replaceable>
} [, ... ]
</synopsis>
<refsect2 id="R2-SQL-CREATEOPCLASS-1">
<refsect2info>
<date>2002-07-28</date>
</refsect2info>
<title>
Inputs
</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">name</replaceable></term>
<listitem>
<para>
The name of the operator class to be created.
The name may be schema-qualified.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>DEFAULT</></term>
<listitem>
<para>
If present, the operator class will become the default index
operator class for its data type. At most one operator class
can be the default for a specific data type and access method.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">data_type</replaceable></term>
<listitem>
<para>
The column data type that this operator class is for.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">access_method</replaceable></term>
<listitem>
<para>
The name of the index access method this operator class is for.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">strategy_number</replaceable></term>
<listitem>
<para>
The index access method's strategy number for an operator associated
with the operator class.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">operator_id</replaceable></term>
<listitem>
<para>
The identifier (optionally schema-qualified) of an operator associated
with the operator class.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">type</replaceable></term>
<listitem>
<para>
The input data type(s) of an operator, or <literal>NONE</> to
signify a left-unary or right-unary operator. The input data types
may be omitted in the normal case where they are the same as the
operator class's data type.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>RECHECK</></term>
<listitem>
<para>
If present, the index is <quote>lossy</> for this operator,
and so the tuples retrieved using the index must be rechecked
to verify that they actually satisfy the qualification clause
involving this operator.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">support_number</replaceable></term>
<listitem>
<para>
The index access method's support procedure number for a function
associated with the operator class.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">func_name</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of a function that is
an index access method support procedure for the operator class.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">parameter_types</replaceable></term>
<listitem>
<para>
The parameter data type(s) of the function.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">storage_type</replaceable></term>
<listitem>
<para>
The data type actually stored in the index. Normally this is the
same as the column data type, but some index access methods (only
GIST at this writing) allow it to be different. The
<literal>STORAGE</> clause must be omitted unless the index access
method allows a different type to be used.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect2>
<refsect2 id="R2-SQL-CREATEOPCLASS-2">
<refsect2info>
<date>2002-07-28</date>
</refsect2info>
<title>
Outputs
</title>
<para>
<variablelist>
<varlistentry>
<term><computeroutput>
CREATE OPERATOR CLASS
</computeroutput></term>
<listitem>
<para>
Message returned if the operator class is successfully created.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect2>
</synopsis>
</refsynopsisdiv>
<refsect1 id="R1-SQL-CREATEOPCLASS-1">
<refsect1info>
<date>2002-07-28</date>
</refsect1info>
<title>
Description
</title>
<para>
<command>CREATE OPERATOR CLASS</command> defines a new operator class,
<replaceable class="parameter">name</replaceable>.
</para>
<refsect1>
<title>Description</title>
<para>
<command>CREATE OPERATOR CLASS</command> creates a new operator class.
An operator class defines how a particular data type can be used with
an index. The operator class specifies that certain operators will fill
particular roles or <quote>strategies</> for this data type and this
access method. The operator class also specifies the support procedures to
index method. The operator class also specifies the support procedures to
be used by
the index access method when the operator class is selected for an
the index method when the operator class is selected for an
index column. All the operators and functions used by an operator
class must be defined before the operator class is created.
</para>
<para>
If a schema name is given then the operator class is created in the
specified schema. Otherwise it is created in the current schema (the one
at the front of the search path; see <literal>CURRENT_SCHEMA()</>).
specified schema. Otherwise it is created in the current schema.
Two operator classes in the same schema can have the same name only if they
are for different index access methods.
are for different index methods.
</para>
<para>
The user who defines an operator class becomes its owner. Presently,
the creating user must be a superuser. (This restriction is made because
@@ -217,41 +55,187 @@ CREATE OPERATOR CLASS
<para>
<command>CREATE OPERATOR CLASS</command> does not presently check
whether the class definition includes all the operators and functions
required by the index access method. It is the user's
whether the operator class definition includes all the operators and functions
required by the index method. It is the user's
responsibility to define a valid operator class.
</para>
<para>
Refer to <xref linkend="xindex"> for further information.
</para>
<refsect2 id="R2-SQL-CREATEOPCLASS-3">
<refsect2info>
<date>2002-07-28</date>
</refsect2info>
<title>
Notes
</title>
<para>
Refer to
<xref linkend="sql-dropopclass" endterm="sql-dropopclass-title">
to delete user-defined operator classes from a database.
</para>
</refsect2>
</refsect1>
<refsect1 id="R1-SQL-CREATEOPCLASS-2">
<title>
Usage
</title>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">name</replaceable></term>
<listitem>
<para>
The name of the operator class to be created. The name may be
schema-qualified.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>DEFAULT</></term>
<listitem>
<para>
If present, the operator class will become the default
operator class for its data type. At most one operator class
can be the default for a specific data type and index method.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">data_type</replaceable></term>
<listitem>
<para>
The column data type that this operator class is for.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">index_method</replaceable></term>
<listitem>
<para>
The name of the index method this operator class is for.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">strategy_number</replaceable></term>
<listitem>
<para>
The index method's strategy number for an operator
associated with the operator class.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">operator_name</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of an operator associated
with the operator class.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">op_type</replaceable></term>
<listitem>
<para>
The operand data type(s) of an operator, or <literal>NONE</> to
signify a left-unary or right-unary operator. The operand data
types may be omitted in the normal case where they are the same
as the operator class's data type.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>RECHECK</></term>
<listitem>
<para>
If present, the index is <quote>lossy</> for this operator, and
so the rows retrieved using the index must be rechecked to
verify that they actually satisfy the qualification clause
involving this operator.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">support_number</replaceable></term>
<listitem>
<para>
The index method's support procedure number for a
function associated with the operator class.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">func_name</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of a function that is an
index method support procedure for the operator class.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">argument_types</replaceable></term>
<listitem>
<para>
The parameter data type(s) of the function.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">storage_type</replaceable></term>
<listitem>
<para>
The data type actually stored in the index. Normally this is
the same as the column data type, but some index methods
(only GiST at this writing) allow it to be different. The
<literal>STORAGE</> clause must be omitted unless the index
method allows a different type to be used.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
The <literal>OPERATOR</>, <literal>FUNCTION</>, and <literal>STORAGE</>
clauses may appear in any order.
</para>
</refsect1>
<refsect1>
<title>Diagnostics</title>
<variablelist>
<varlistentry>
<term><computeroutput>CREATE OPERATOR CLASS</computeroutput></term>
<listitem>
<para>
Message returned if the operator class was successfully created.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
Refer to
<xref linkend="sql-dropopclass" endterm="sql-dropopclass-title">
to delete user-defined operator classes from a database.
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
The following example command defines a GiST index operator class
for data type <literal>_int4</> (array of int4). See
for the data type <literal>_int4</> (array of <type>int4</type>). See
<filename>contrib/intarray/</> for the complete example.
</para>
<programlisting>
<programlisting>
CREATE OPERATOR CLASS gist__int_ops
DEFAULT FOR TYPE _int4 USING gist AS
OPERATOR 3 &&,
@@ -266,34 +250,18 @@ CREATE OPERATOR CLASS gist__int_ops
FUNCTION 5 g_int_penalty (internal, internal, internal),
FUNCTION 6 g_int_picksplit (internal, internal),
FUNCTION 7 g_int_same (_int4, _int4, internal);
</programlisting>
<para>
The <literal>OPERATOR</>, <literal>FUNCTION</>, and <literal>STORAGE</>
clauses may appear in any order.
</para>
</programlisting>
</refsect1>
<refsect1 id="R1-SQL-CREATEOPCLASS-3">
<title>
Compatibility
</title>
<refsect2 id="R2-SQL-CREATEOPCLASS-4">
<refsect2info>
<date>2002-07-28</date>
</refsect2info>
<title>
SQL92
</title>
<refsect1>
<title>Compatibility</title>
<para>
<command>CREATE OPERATOR CLASS</command>
is a <productname>PostgreSQL</productname> extension.
There is no <command>CREATE OPERATOR CLASS</command>
statement in <acronym>SQL92</acronym>.
</para>
</refsect2>
<para>
<command>CREATE OPERATOR CLASS</command> is a
<productname>PostgreSQL</productname> extension. There is no
<command>CREATE OPERATOR CLASS</command> statement in the SQL
standard.
</para>
</refsect1>
</refentry>