NAME¶

CREATE_OPERATOR - define a new operator

SYNOPSIS¶

CREATE OPERATOR name (


    {FUNCTION|PROCEDURE} = function_name


    [, LEFTARG = left_type ] [, RIGHTARG = right_type ]


    [, COMMUTATOR = com_op ] [, NEGATOR = neg_op ]


    [, RESTRICT = res_proc ] [, JOIN = join_proc ]


    [, HASHES ] [, MERGES ]
)

DESCRIPTION¶

CREATE OPERATOR defines a new operator, name. The user who defines an operator becomes its owner. If a schema name is given then the operator is created in the specified schema. Otherwise it is created in the current schema.

The operator name is a sequence of up to NAMEDATALEN-1 (63 by default) characters from the following list:

+ - * / < > = ~ ! @ # % ^ & | ` ?

There are a few restrictions on your choice of name:

~ ! @ # % ^ & | ` ?

The operator != is mapped to <> on input, so these two names are always equivalent.

For binary operators, both LEFTARG and RIGHTARG must be defined. For prefix operators only RIGHTARG should be defined. The function_name function must have been previously defined using CREATE FUNCTION and must be defined to accept the correct number of arguments (either one or two) of the indicated types.

In the syntax of CREATE OPERATOR, the keywords FUNCTION and PROCEDURE are equivalent, but the referenced function must in any case be a function, not a procedure. The use of the keyword PROCEDURE here is historical and deprecated.

The other clauses specify optional operator optimization attributes. Their meaning is detailed in Section 36.15.

To be able to create an operator, you must have USAGE privilege on the argument types and the return type, as well as EXECUTE privilege on the underlying function. If a commutator or negator operator is specified, you must own those operators.

PARAMETERS¶

name

function_name

left_type

right_type

com_op

neg_op

res_proc

join_proc

HASHES

MERGES

To give a schema-qualified operator name in com_op or the other optional arguments, use the OPERATOR() syntax, for example:

COMMUTATOR = OPERATOR(myschema.===) ,

NOTES¶

Refer to Section 36.14 and Section 36.15 for further information.

When you are defining a self-commutative operator, you just do it. When you are defining a pair of commutative operators, things are a little trickier: how can the first one to be defined refer to the other one, which you haven't defined yet? There are three solutions to this problem:

In all three cases, you must own both operators in order to mark them as commutators.

Pairs of negator operators can be defined using the same methods as for commutator pairs.

It is not possible to specify an operator's lexical precedence in CREATE OPERATOR, because the parser's precedence behavior is hard-wired. See Section 4.1.6 for precedence details.

The obsolete options SORT1, SORT2, LTCMP, and GTCMP were formerly used to specify the names of sort operators associated with a merge-joinable operator. This is no longer necessary, since information about associated operators is found by looking at B-tree operator families instead. If one of these options is given, it is ignored except for implicitly setting MERGES true.

Use DROP OPERATOR to delete user-defined operators from a database. Use ALTER OPERATOR to modify operators in a database.

EXAMPLES¶

The following command defines a new operator, area-equality, for the data type box:

CREATE OPERATOR === (


    LEFTARG = box,


    RIGHTARG = box,


    FUNCTION = area_equal_function,


    COMMUTATOR = ===,


    NEGATOR = !==,


    RESTRICT = area_restriction_function,


    JOIN = area_join_function,


    HASHES, MERGES
);

COMPATIBILITY¶

CREATE OPERATOR is a PostgreSQL extension. There are no provisions for user-defined operators in the SQL standard.

SEE ALSO¶

ALTER OPERATOR (ALTER_OPERATOR(7)), CREATE OPERATOR CLASS (CREATE_OPERATOR_CLASS(7)), DROP OPERATOR (DROP_OPERATOR(7))