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We've accumulated quite a mix of instances of "an SQL" and "a SQL" in the documents. It would be good to be a bit more consistent with these. The most recent version of the SQL standard I looked at seems to prefer "an SQL". That seems like a good lead to follow, so here we change all instances of "a SQL" to become "an SQL". Most instances correctly use "an SQL" already, so it also makes sense to use the dominant variation in order to minimise churn. Additionally, there were some other abbreviations that needed to be adjusted. FSM, SSPI, SRF and a few others. Also fix some pronounceable, abbreviations to use "a" instead of "an". For example, "a SASL" instead of "an SASL". Here I've only adjusted the documents and error messages. Many others still exist in source code comments. Translator hint comments seem to be the biggest culprit. It currently does not seem worth the churn to change these. Discussion: https://postgr.es/m/CAApHDvpML27UqFXnrYO1MJddsKVMQoiZisPvsAGhKE_tsKXquw%40mail.gmail.com
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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