CREATE OPERATOR() SQL Commands CREATE OPERATOR()
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 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 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 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.
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-joinable
operator. This is no longer necessary, since information about associ-
ated 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(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, 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(l)], CREATE OPERATOR CLASS [create_oper-
ator_class(l)], DROP OPERATOR [drop_operator(l)]
SQL - Language Statements 2008-09-19 CREATE OPERATOR()
postgresql 8.3.4 - Generated Thu Oct 2 11:44:14 CDT 2008