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 opera-
       tor 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 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  argu-
       ments (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 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 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 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-join-
       able 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)]

SQL - Language Statements					    2010-05-14							CREATE OPERATOR(7)