|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.
o The use of => as an operator name is deprecated. It may be disallowed altogether in a future release.
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 35.13, 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.
nameThe 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.
function_nameThe function used to implement this operator.
left_typeThe data type of the operators left operand, if any. This option would be omitted for a left-unary operator.
right_typeThe data type of the operators right operand, if any. This option would be omitted for a right-unary operator.
com_opThe commutator of this operator.
neg_opThe negator of this operator.
res_procThe restriction selectivity estimator function for this operator.
join_procThe join selectivity estimator function for this operator.
HASHESIndicates this operator can support a hash join.
MERGESIndicates 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.===) ,
Refer to Section 35.12, User-defined Operators, in the documentation for further information.
It is not possible to specify an operators lexical precedence in CREATE OPERATOR, because the parsers 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.
ALTER OPERATOR (ALTER_OPERATOR(7)), CREATE OPERATOR CLASS (CREATE_OPERATOR_CLASS(7)), DROP OPERATOR (DROP_OPERATOR(7))
|PostgreSQL 9.5.2||CREATE OPERATOR (7)||2016|