xenial (7) CREATE_OPERATOR.7.gz

NAME

       CREATE_OPERATOR - define a new operator

SYNOPSIS

       CREATE OPERATOR name (
           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:

       •   -- and /* cannot appear anywhere in an operator name, since they will be taken as the start of a
           comment.

       •   A multicharacter operator name cannot end in + or -, unless the name also contains at least one of
           these characters:

               ~ ! @ # % ^ & | ` ?

           For example, @- is an allowed operator name, but *- is not. This restriction allows PostgreSQL to
           parse SQL-compliant commands without requiring spaces between tokens.

       •   The use of => as an operator name is deprecated. It may be disallowed altogether in a future release.

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

       At least one of LEFTARG and RIGHTARG must be defined. For binary operators, both must be defined. For
       right unary operators, only LEFTARG should be defined, while for left unary operators only RIGHTARG
       should be defined.

           Note
           Right unary, also called postfix, operators are deprecated and will be removed in PostgreSQL version
           14.

       The function_name procedure 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.

       The other clauses specify optional operator optimization clauses. Their meaning is detailed in Section
       35.13, “Operator Optimization Information”, in the documentation.

       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 these operators.

PARAMETERS

       name
           The name of the operator to be defined. See above for allowable characters. The name can be
           schema-qualified, for example CREATE OPERATOR myschema.+ (...). If not, then the operator is created
           in the current schema. Two operators in the same schema can have the same name if they operate on
           different data types. This is called overloading.

       function_name
           The function used to implement this operator.

       left_type
           The data type of the operator's left operand, if any. This option would be omitted for a left-unary
           operator.

       right_type
           The data type of the operator's right operand, if any. This option would be omitted for a right-unary
           operator.

       com_op
           The commutator of this operator.

       neg_op
           The negator of this operator.

       res_proc
           The restriction selectivity estimator function for this operator.

       join_proc
           The join selectivity estimator function for this operator.

       HASHES
           Indicates this operator can support a hash join.

       MERGES
           Indicates this operator can support a merge join.

       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 35.12, “User-defined Operators”, in the documentation for further information.

       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, “Operator Precedence”, in the documentation 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 (DROP_OPERATOR(7)) to delete user-defined operators from a database. Use ALTER OPERATOR
       (ALTER_OPERATOR(7)) 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,
               PROCEDURE = area_equal_procedure,
               COMMUTATOR = ===,
               NEGATOR = !==,
               RESTRICT = area_restriction_procedure,
               JOIN = area_join_procedure,
               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))