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CREATE OPERATOR(7) PostgreSQL 12.18 Documentation CREATE OPERATOR(7)
NAME
CREATE_OPERATOR - define a new operator
SYNOPSIS
CREATE OPERATOR name (
{FUNCTION|PROCEDURE} = function_name
[, LEFTARG = left_type ] [, RIGHTARG = right_type ]
[, 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.
o The symbol => is reserved by the SQL grammar, so it cannot be used as an operator
name.
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.
Note
Right unary, also called postfix, operators are deprecated and will be removed in
PostgreSQL version 14.
The function_name function 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.
In the syntax of CREATE OPERATOR, the keywords FUNCTION and PROCEDURE are equivalent, but
the referenced function must in any case be a function, not a procedure. The use of the
keyword PROCEDURE here is historical and deprecated.
The other clauses specify optional operator optimization clauses. Their meaning is
detailed in Section 37.15.
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.
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.
function_name
The function used to implement this operator.
left_type
The data type of the operator's left operand, if any. This option would be omitted for
a left-unary operator.
right_type
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 Section 37.14 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 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.
EXAMPLES
The following command defines a new operator, area-equality, for the data type box:
CREATE OPERATOR === (
LEFTARG = box,
RIGHTARG = box,
FUNCTION = area_equal_function,
COMMUTATOR = ===,
NEGATOR = !==,
RESTRICT = area_restriction_function,
JOIN = area_join_function,
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))
PostgreSQL 12.18 2024 CREATE OPERATOR(7)
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