# 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                                                  |
| :------------- | :------ | :--------------- | :----------------------------------------------------------- |
| `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) |
| `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`    |         | pg_operator.oid  | Negator of this operator, if any.                            |
| `oprlsortop`   | oid     | pg_operator.oid  | If this operator supports merge joins, the operator that sorts the type of the left-hand operand (`L<L`). |
| `oprrsortop`   | oid     | pg_operator.oid  | If this operator supports merge joins, the operator that sorts the type of the right-hand operand (`R<R`). |
| `oprltcmpop`   | oid     | pg_operator.oid  | If this operator supports merge joins, the less-than operator that compares the left and right operand types (`L<R`). |
| `oprgtcmpop`   | oid     | pg_operator.oid  | If this operator supports merge joins, the greater-than operator that compares the left and right operand types (`L>R`). |
| `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.      |