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CREATE OPERATOR(7)	 PostgreSQL 17.5 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:

          -- and /* cannot appear anywhere in an operator name, since they
	   will	be taken as the	start of a comment.

          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 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.

       For binary operators, both LEFTARG and RIGHTARG must be defined.	For
       prefix operators	only RIGHTARG should be	defined. 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	attributes.
       Their meaning is	detailed in Section 36.15.

       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 those 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 prefix operator.

       right_type
	   The data type of the	operator's right operand.

       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	36.14 and Section 36.15	for further information.

       When you	are defining a self-commutative	operator, you just do it. When
       you are defining	a pair of commutative operators, things	are a little
       trickier: how can the first one to be defined refer to the other	one,
       which you haven't defined yet? There are	three solutions	to this
       problem:

          One way is to omit the COMMUTATOR clause in the first operator that
	   you define, and then	provide	one in the second operator's
	   definition. Since PostgreSQL	knows that commutative operators come
	   in pairs, when it sees the second definition	it will	automatically
	   go back and fill in the missing COMMUTATOR clause in	the first
	   definition.

          Another, more straightforward way is	just to	include	COMMUTATOR
	   clauses in both definitions.	When PostgreSQL	processes the first
	   definition and realizes that	COMMUTATOR refers to a nonexistent
	   operator, the system	will make a dummy entry	for that operator in
	   the system catalog. This dummy entry	will have valid	data only for
	   the operator	name, left and right operand types, and	owner, since
	   that's all that PostgreSQL can deduce at this point.	The first
	   operator's catalog entry will link to this dummy entry. Later, when
	   you define the second operator, the system updates the dummy	entry
	   with	the additional information from	the second definition. If you
	   try to use the dummy	operator before	it's been filled in, you'll
	   just	get an error message.

          Alternatively, both operators can be	defined	without	COMMUTATOR
	   clauses and then ALTER OPERATOR can be used to set their commutator
	   links. It's sufficient to ALTER either one of the pair.

       In all three cases, you must own	both operators in order	to mark	them
       as commutators.

       Pairs of	negator	operators can be defined using the same	methods	as for
       commutator pairs.

       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 to delete user-defined	operators from a database. Use
       ALTER OPERATOR 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 17.5			     2025		    CREATE OPERATOR(7)

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