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<!--
doc/src/sgml/ref/alter_operator.sgml
PostgreSQL documentation
-->
<refentry id="sql-alteroperator">
<indexterm zone="sql-alteroperator">
<primary>ALTER OPERATOR</primary>
</indexterm>
<refmeta>
<refentrytitle>ALTER OPERATOR</refentrytitle>
<manvolnum>7</manvolnum>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>ALTER OPERATOR</refname>
<refpurpose>change the definition of an operator</refpurpose>
</refnamediv>
<refsynopsisdiv>
<synopsis>
ALTER OPERATOR <replaceable>name</replaceable> ( { <replaceable>left_type</replaceable> | NONE } , <replaceable>right_type</replaceable> )
OWNER TO { <replaceable>new_owner</replaceable> | CURRENT_ROLE | CURRENT_USER | SESSION_USER }
ALTER OPERATOR <replaceable>name</replaceable> ( { <replaceable>left_type</replaceable> | NONE } , <replaceable>right_type</replaceable> )
SET SCHEMA <replaceable>new_schema</replaceable>
ALTER OPERATOR <replaceable>name</replaceable> ( { <replaceable>left_type</replaceable> | NONE } , <replaceable>right_type</replaceable> )
SET ( { RESTRICT = { <replaceable class="parameter">res_proc</replaceable> | NONE }
| JOIN = { <replaceable class="parameter">join_proc</replaceable> | NONE }
| COMMUTATOR = <replaceable class="parameter">com_op</replaceable>
| NEGATOR = <replaceable class="parameter">neg_op</replaceable>
| HASHES
| MERGES
} [, ... ] )
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<command>ALTER OPERATOR</command> changes the definition of
an operator.
</para>
<para>
You must own the operator to use <command>ALTER OPERATOR</command>.
To alter the owner, you must be able to <literal>SET ROLE</literal> to the
new owning role, and that role must have <literal>CREATE</literal>
privilege on the operator's schema.
(These restrictions enforce that altering the owner
doesn't do anything you couldn't do by dropping and recreating the operator.
However, a superuser can alter ownership of any operator anyway.)
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">name</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of an existing operator.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">left_type</replaceable></term>
<listitem>
<para>
The data type of the operator's left operand; write
<literal>NONE</literal> if the operator has no left operand.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">right_type</replaceable></term>
<listitem>
<para>
The data type of the operator's right operand.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">new_owner</replaceable></term>
<listitem>
<para>
The new owner of the operator.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">new_schema</replaceable></term>
<listitem>
<para>
The new schema for the operator.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">res_proc</replaceable></term>
<listitem>
<para>
The restriction selectivity estimator function for this operator; write NONE to remove existing selectivity estimator.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">join_proc</replaceable></term>
<listitem>
<para>
The join selectivity estimator function for this operator; write NONE to remove existing selectivity estimator.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">com_op</replaceable></term>
<listitem>
<para>
The commutator of this operator. Can only be changed if the operator
does not have an existing commutator.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">neg_op</replaceable></term>
<listitem>
<para>
The negator of this operator. Can only be changed if the operator does
not have an existing negator.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>HASHES</literal></term>
<listitem>
<para>
Indicates this operator can support a hash join. Can only be enabled and
not disabled.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>MERGES</literal></term>
<listitem>
<para>
Indicates this operator can support a merge join. Can only be enabled
and not disabled.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<para>
Refer to <xref linkend="xoper"/> and
<xref linkend="xoper-optimization"/> for further information.
</para>
<para>
Since commutators come in pairs that are commutators of each other,
<literal>ALTER OPERATOR SET COMMUTATOR</literal> will also set the
commutator of the <replaceable class="parameter">com_op</replaceable>
to be the target operator. Likewise, <literal>ALTER OPERATOR SET
NEGATOR</literal> will also set the negator of
the <replaceable class="parameter">neg_op</replaceable> to be the
target operator. Therefore, you must own the commutator or negator
operator as well as the target operator.
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
Change the owner of a custom operator <literal>a @@ b</literal> for type <type>text</type>:
<programlisting>
ALTER OPERATOR @@ (text, text) OWNER TO joe;
</programlisting>
</para>
<para>
Change the restriction and join selectivity estimator functions of a
custom operator <literal>a && b</literal> for
type <type>int[]</type>:
<programlisting>
ALTER OPERATOR && (int[], int[]) SET (RESTRICT = _int_contsel, JOIN = _int_contjoinsel);
</programlisting>
</para>
<para>
Mark the <literal>&&</literal> operator as being its own
commutator:
<programlisting>
ALTER OPERATOR && (int[], int[]) SET (COMMUTATOR = &&);
</programlisting>
</para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para>
There is no <command>ALTER OPERATOR</command> statement in
the SQL standard.
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-createoperator"/></member>
<member><xref linkend="sql-dropoperator"/></member>
</simplelist>
</refsect1>
</refentry>
|
