# pg_operator

The `pg_operator` system catalog table stores information about operators, both built-in and those defined by `CREATE OPERATOR`. Unused column contain zeroes. For example, `oprleft` is zero for a prefix operator.



Table 1. `pg_catalog.pg_operator`

| column         | type    | references       | description                                                  |
| :------------- | :------ | :--------------- | :----------------------------------------------------------- |
|`oid`|	oid ||		Row identifier (hidden attribute, must be explicityly selected)
|`oprname`|	name||		Name of the operator
|`oprnamespace`|	oid	|pg_namespace.oid|	The OID of the namespace that contains this operator
|`oprowner`|	oid	|pg_authid.oid|	Owner of the operator
|`oprkind`|	char||		`b` = infix (both), `l` = prefix (left), `r` = postfix (right)
|`koprcanmerge`|	boolean		||This operator supports merge joins
|`oprcanhash`|	boolean		||This operator supports hash joins
|`oprleft`|	oid	|pg_type.oid	|Type of the left operand
|`oprright`|	oid	|pg_type.oid|	Type of the right operand
|`oprresult`|	oid|	pg_type.oid	|Type of the result
|`oprcom`|	oid	|pg_operator.oid	|Commutator of this operator, if any
|`oprnegate`|	oid	|pg_operator.oid|	Negator of this operator, if any
|`oprcode`|	regproc	|pg_proc.oid	|Function that implements this operator
|`oprrest`|	regproc	|pg_proc.oid	|Restriction selectivity estimation function for this operator
|`oprjoin`|	regproc|	pg_proc.oid	|Join selectivity estimation function for this operator