Provided by: postgresql-client-9.1_9.1.1-1_i386 bug

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:

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

       o   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.

       o   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.

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))