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.

       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))