361 lines
12 KiB
Plaintext
361 lines
12 KiB
Plaintext
<!--
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doc/src/sgml/ref/alter_opfamily.sgml
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PostgreSQL documentation
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-->
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<refentry id="sql-alteropfamily">
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<indexterm zone="sql-alteropfamily">
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<primary>ALTER OPERATOR FAMILY</primary>
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</indexterm>
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<refmeta>
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<refentrytitle>ALTER OPERATOR FAMILY</refentrytitle>
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<manvolnum>7</manvolnum>
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<refmiscinfo>SQL - Language Statements</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>ALTER OPERATOR FAMILY</refname>
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<refpurpose>change the definition of an operator family</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<synopsis>
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ALTER OPERATOR FAMILY <replaceable>name</replaceable> USING <replaceable class="parameter">index_method</replaceable> ADD
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{ 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> )
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[ FOR SEARCH | FOR ORDER BY <replaceable class="parameter">sort_family_name</replaceable> ]
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| FUNCTION <replaceable class="parameter">support_number</replaceable> [ ( <replaceable class="parameter">op_type</replaceable> [ , <replaceable class="parameter">op_type</replaceable> ] ) ]
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<replaceable class="parameter">function_name</replaceable> [ ( <replaceable class="parameter">argument_type</replaceable> [, ...] ) ]
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} [, ... ]
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ALTER OPERATOR FAMILY <replaceable>name</replaceable> USING <replaceable class="parameter">index_method</replaceable> DROP
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{ OPERATOR <replaceable class="parameter">strategy_number</replaceable> ( <replaceable class="parameter">op_type</replaceable> [ , <replaceable class="parameter">op_type</replaceable> ] )
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| FUNCTION <replaceable class="parameter">support_number</replaceable> ( <replaceable class="parameter">op_type</replaceable> [ , <replaceable class="parameter">op_type</replaceable> ] )
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} [, ... ]
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ALTER OPERATOR FAMILY <replaceable>name</replaceable> USING <replaceable class="parameter">index_method</replaceable>
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RENAME TO <replaceable>new_name</replaceable>
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ALTER OPERATOR FAMILY <replaceable>name</replaceable> USING <replaceable class="parameter">index_method</replaceable>
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OWNER TO { <replaceable>new_owner</replaceable> | CURRENT_ROLE | CURRENT_USER | SESSION_USER }
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ALTER OPERATOR FAMILY <replaceable>name</replaceable> USING <replaceable class="parameter">index_method</replaceable>
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SET SCHEMA <replaceable>new_schema</replaceable>
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</synopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>
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<command>ALTER OPERATOR FAMILY</command> changes the definition of
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an operator family. You can add operators and support functions
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to the family, remove them from the family,
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or change the family's name or owner.
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</para>
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<para>
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When operators and support functions are added to a family with
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<command>ALTER OPERATOR FAMILY</command>, they are not part of any
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specific operator class within the family, but are just <quote>loose</quote>
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within the family. This indicates that these operators and functions
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are compatible with the family's semantics, but are not required for
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correct functioning of any specific index. (Operators and functions
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that are so required should be declared as part of an operator class,
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instead; see <xref linkend="sql-createopclass"/>.)
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<productname>PostgreSQL</productname> will allow loose members of a
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family to be dropped from the family at any time, but members of an
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operator class cannot be dropped without dropping the whole class and
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any indexes that depend on it.
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Typically, single-data-type operators
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and functions are part of operator classes because they are needed to
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support an index on that specific data type, while cross-data-type
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operators and functions are made loose members of the family.
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</para>
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<para>
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You must be a superuser to use <command>ALTER OPERATOR FAMILY</command>.
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(This restriction is made because an erroneous operator family definition
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could confuse or even crash the server.)
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</para>
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<para>
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<command>ALTER OPERATOR FAMILY</command> does not presently check
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whether the operator family definition includes all the operators and
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functions required by the index method, nor whether the operators and
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functions form a self-consistent set. It is the user's
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responsibility to define a valid operator family.
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</para>
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<para>
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Refer to <xref linkend="xindex"/> for further information.
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</para>
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</refsect1>
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<refsect1>
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<title>Parameters</title>
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<variablelist>
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<varlistentry>
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<term><replaceable class="parameter">name</replaceable></term>
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<listitem>
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<para>
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The name (optionally schema-qualified) of an existing operator
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family.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">index_method</replaceable></term>
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<listitem>
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<para>
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The name of the index method this operator family is for.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">strategy_number</replaceable></term>
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<listitem>
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<para>
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The index method's strategy number for an operator
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associated with the operator family.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">operator_name</replaceable></term>
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<listitem>
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<para>
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The name (optionally schema-qualified) of an operator associated
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with the operator family.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">op_type</replaceable></term>
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<listitem>
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<para>
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In an <literal>OPERATOR</literal> clause,
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the operand data type(s) of the operator, or <literal>NONE</literal> to
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signify a prefix operator. Unlike the comparable
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syntax in <command>CREATE OPERATOR CLASS</command>, the operand data types
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must always be specified.
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</para>
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<para>
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In an <literal>ADD FUNCTION</literal> clause, the operand data type(s) the
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function is intended to support, if different from
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the input data type(s) of the function. For B-tree comparison functions
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and hash functions it is not necessary to specify <replaceable
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class="parameter">op_type</replaceable> since the function's input
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data type(s) are always the correct ones to use. For B-tree sort
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support functions, B-Tree equal image functions, and all
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functions in GiST, SP-GiST and GIN operator classes, it is
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necessary to specify the operand data type(s) the function is to
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be used with.
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</para>
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<para>
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In a <literal>DROP FUNCTION</literal> clause, the operand data type(s) the
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function is intended to support must be specified.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">sort_family_name</replaceable></term>
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<listitem>
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<para>
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The name (optionally schema-qualified) of an existing <literal>btree</literal> operator
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family that describes the sort ordering associated with an ordering
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operator.
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</para>
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<para>
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If neither <literal>FOR SEARCH</literal> nor <literal>FOR ORDER BY</literal> is
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specified, <literal>FOR SEARCH</literal> is the default.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">support_number</replaceable></term>
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<listitem>
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<para>
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The index method's support function number for a
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function associated with the operator family.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">function_name</replaceable></term>
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<listitem>
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<para>
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The name (optionally schema-qualified) of a function that is an index
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method support function for the operator family. If no argument list
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is specified, the name must be unique in its schema.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">argument_type</replaceable></term>
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<listitem>
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<para>
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The parameter data type(s) of the function.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">new_name</replaceable></term>
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<listitem>
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<para>
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The new name of the operator family.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">new_owner</replaceable></term>
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<listitem>
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<para>
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The new owner of the operator family.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="parameter">new_schema</replaceable></term>
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<listitem>
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<para>
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The new schema for the operator family.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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<para>
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The <literal>OPERATOR</literal> and <literal>FUNCTION</literal>
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clauses can appear in any order.
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</para>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>
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Notice that the <literal>DROP</literal> syntax only specifies the <quote>slot</quote>
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in the operator family, by strategy or support number and input data
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type(s). The name of the operator or function occupying the slot is not
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mentioned. Also, for <literal>DROP FUNCTION</literal> the type(s) to specify
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are the input data type(s) the function is intended to support; for
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GiST, SP-GiST and GIN indexes this might have nothing to do with the actual
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input argument types of the function.
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</para>
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<para>
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Because the index machinery does not check access permissions on functions
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before using them, including a function or operator in an operator family
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is tantamount to granting public execute permission on it. This is usually
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not an issue for the sorts of functions that are useful in an operator
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family.
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</para>
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<para>
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The operators should not be defined by SQL functions. An SQL function
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is likely to be inlined into the calling query, which will prevent
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the optimizer from recognizing that the query matches an index.
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</para>
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<para>
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Before <productname>PostgreSQL</productname> 8.4, the <literal>OPERATOR</literal>
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clause could include a <literal>RECHECK</literal> option. This is no longer
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supported because whether an index operator is <quote>lossy</quote> is now
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determined on-the-fly at run time. This allows efficient handling of
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cases where an operator might or might not be lossy.
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</para>
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</refsect1>
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<refsect1>
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<title>Examples</title>
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<para>
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The following example command adds cross-data-type operators and
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support functions to an operator family that already contains B-tree
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operator classes for data types <type>int4</type> and <type>int2</type>.
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</para>
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<programlisting>
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ALTER OPERATOR FAMILY integer_ops USING btree ADD
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-- int4 vs int2
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OPERATOR 1 < (int4, int2) ,
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OPERATOR 2 <= (int4, int2) ,
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OPERATOR 3 = (int4, int2) ,
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OPERATOR 4 >= (int4, int2) ,
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OPERATOR 5 > (int4, int2) ,
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FUNCTION 1 btint42cmp(int4, int2) ,
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-- int2 vs int4
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OPERATOR 1 < (int2, int4) ,
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OPERATOR 2 <= (int2, int4) ,
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OPERATOR 3 = (int2, int4) ,
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OPERATOR 4 >= (int2, int4) ,
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OPERATOR 5 > (int2, int4) ,
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FUNCTION 1 btint24cmp(int2, int4) ;
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</programlisting>
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<para>
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To remove these entries again:
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</para>
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<programlisting>
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ALTER OPERATOR FAMILY integer_ops USING btree DROP
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-- int4 vs int2
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OPERATOR 1 (int4, int2) ,
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OPERATOR 2 (int4, int2) ,
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OPERATOR 3 (int4, int2) ,
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OPERATOR 4 (int4, int2) ,
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OPERATOR 5 (int4, int2) ,
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FUNCTION 1 (int4, int2) ,
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-- int2 vs int4
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OPERATOR 1 (int2, int4) ,
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OPERATOR 2 (int2, int4) ,
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OPERATOR 3 (int2, int4) ,
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OPERATOR 4 (int2, int4) ,
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OPERATOR 5 (int2, int4) ,
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FUNCTION 1 (int2, int4) ;
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</programlisting>
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</refsect1>
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<refsect1>
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<title>Compatibility</title>
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<para>
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There is no <command>ALTER OPERATOR FAMILY</command> statement in
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the SQL standard.
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</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<simplelist type="inline">
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<member><xref linkend="sql-createopfamily"/></member>
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<member><xref linkend="sql-dropopfamily"/></member>
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<member><xref linkend="sql-createopclass"/></member>
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<member><xref linkend="sql-alteropclass"/></member>
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<member><xref linkend="sql-dropopclass"/></member>
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</simplelist>
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</refsect1>
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</refentry>
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