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Implement CREATE/DROP OPERATOR CLASS. Work still remains: need more

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documentation (xindex.sgml should be rewritten), need to teach pg_dump
about it, need to update contrib modules that currently build pg_opclass
entries by hand.  Original patch by Bill Studenmund, grammar adjustments
and general update for 7.3 by Tom Lane.
This commit is contained in:
Tom Lane
2002-07-29 22:14:11 +00:00
parent b9459c6adb
commit ea4686e3e1
26 changed files with 1697 additions and 373 deletions
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doc/src/sgml/ref/create_opclass.sgml Normal file
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<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_opclass.sgml,v 1.1 2002/07/29 22:14:10 tgl Exp $
PostgreSQL documentation
-->
<refentry id="SQL-CREATEOPCLASS">
<refmeta>
<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>
<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> )
| 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 datatype. At most one operator class
can be the default for a specific datatype and access method.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">data_type</replaceable></term>
<listitem>
<para>
The column datatype 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 datatype(s) of an operator, or <literal>NONE</> to
signify a left-unary or right-unary operator. The input datatypes
may be omitted in the normal case where they are the same as the
operator class's datatype.
</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 datatype(s) of the function.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">storage_type</replaceable></term>
<listitem>
<para>
The datatype actually stored in the index. Normally this is the
same as the column datatype, 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>
</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>
<para>
An operator class defines how a particular datatype can be used with
an index. The operator class specifies that certain operators will fill
particular roles or <quote>strategies</> for this datatype and this
access 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
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()</>).
Two operator classes in the same schema can have the same name only if they
are for different index access methods.
</para>
<para>
The user who defines an operator class becomes its owner. The user
must own the datatype for which the operator class is being defined,
and must have execute permission for all referenced operators and functions.
</para>
<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
responsibility to define a valid operator class.
</para>
<para>
Refer to the chapter on interfacing extensions to indexes in the
<citetitle>PostgreSQL Programmer's Guide</citetitle>
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>
<para>
The following example command defines a GiST index operator class
for datatype <literal>_int4</> (array of int4). See
<filename>contrib/intarray/</> for the complete example.
</para>
<programlisting>
CREATE OPERATOR CLASS gist__int_ops
DEFAULT FOR TYPE _int4 USING gist AS
OPERATOR 3 &&,
OPERATOR 6 = RECHECK,
OPERATOR 7 @,
OPERATOR 8 ~,
OPERATOR 20 @@ (_int4, query_int),
FUNCTION 1 g_int_consistent (opaque, _int4, int4),
FUNCTION 2 g_int_union (bytea, opaque),
FUNCTION 3 g_int_compress (opaque),
FUNCTION 4 g_int_decompress (opaque),
FUNCTION 5 g_int_penalty (opaque, opaque, opaque),
FUNCTION 6 g_int_picksplit (opaque, opaque),
FUNCTION 7 g_int_same (_int4, _int4, opaque);
</programlisting>
<para>
The <literal>OPERATOR</>, <literal>FUNCTION</>, and <literal>STORAGE</>
clauses may appear in any order.
</para>
</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>
<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>
</refsect1>
</refentry>
<!-- Keep this comment at the end of the file
Local variables:
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sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
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sgml-parent-document:nil
sgml-default-dtd-file:"../reference.ced"
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sgml-local-ecat-files:nil
End:
-->