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 ] )
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:
~ ! @ # % ^ & | ` ?
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 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 36.13, "Operator Optimization Information", in the documentation.
To be able to create an operator, you must have USAGE privilege on the argument types and the return type, as well as EXECUTE privilege on the underlying function. If a commutator or negator operator is specified, you must own these operators.
To give a schema-qualified operator name in com_op or the other optional arguments, use the OPERATOR() syntax, for example:
COMMUTATOR = OPERATOR(myschema.===) ,
Refer to Section 36.12, "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.
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 );
CREATE OPERATOR is a PostgreSQL extension. There are no provisions for user-defined operators in the SQL standard.