CREATE OPERATOR(7)                                        SQL Commands                                        CREATE OPERATOR(7)



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 ]
       )


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.

       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 opera-
       tors, 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 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  opera-
              tors  in  the same schema can have the same name if they operate on different data types. This is called overload-
              ing.

       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 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  exam-
       ple:

       COMMUTATOR = OPERATOR(myschema.===) ,


NOTES
       Refer to in the documentation for further information.

       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 set-
       ting MERGES true.

       Use DROP OPERATOR [drop_operator(7)] to delete user-defined operators from a database. Use ALTER  OPERATOR  [alter_opera-
       tor(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)]



SQL - Language Statements                                  2011-09-22                                         CREATE OPERATOR(7)