/usr/man2/cat.l/create_operator.l.Z

NAME

       CREATE OPERATOR - define a new operator

SYNOPSIS

       CREATE OPERATOR name (
           PROCEDURE = funcname
           [, LEFTARG = lefttype ] [, RIGHTARG = righttype ]
           [, COMMUTATOR = com_op ] [, NEGATOR = neg_op ]
           [, RESTRICT = res_proc ] [, JOIN = join_proc ]
           [, HASHES ] [, MERGES ]
           [, SORT1 = left_sort_op ] [, SORT2 = right_sort_op ]
           [, LTCMP = less_than_op ] [, GTCMP = greater_than_op ]
       )

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 cur-
       rent 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.

       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 opera-
       tors,  both  must  be  defined. For right unary operators, only LEFTARG
       should be defined, while for left unary operators only RIGHTARG  should
       be defined.

       The  funcname  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 the documentation.

PARAMETERS

       name   The name of the operator to be defined. See above for  allowable
              characters. The name may 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.

       funcname
              The function used to implement this operator.

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

       righttype
              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 opera-
              tor.

       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.

       left_sort_op
              If this operator can support a merge join, the less-than  opera-
              tor that sorts the left-hand data type of this operator.

       right_sort_op
              If  this operator can support a merge join, the less-than opera-
              tor that sorts the right-hand data type of this operator.

       less_than_op
              If this operator can support a merge join, the less-than  opera-
              tor that compares the input data types of this operator.

       greater_than_op
              If  this  operator  can  support  a merge join, the greater-than
              operator that compares the input data types of this operator.

       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 the documentation for further information.

       Use  DROP  OPERATOR [drop_operator(l)] to delete user-defined operators
       from a database. Use ALTER OPERATOR [alter_operator(l)] to modify oper-
       ators 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,
           SORT1 = <<<,
           SORT2 = <<<
           -- Since sort operators were given, MERGES is implied.
           -- LTCMP and GTCMP are assumed to be < and > respectively
       );

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(l)], CREATE OPERATOR CLASS [create_oper-
       ator_class(l)], DROP OPERATOR [drop_operator(l)]

SQL - Language Statements         2005-11-05                 CREATE OPERATOR()