# pg_amop

The `pg_amop` table stores information about operators associated with index access method operator classes. There is one row for each operator that is a member of an operator class.

An entry's `amopmethod` must match the `opfmethod` of its containing operator family (including `amopmethod` here is an intentional denormalization of the catalog structure for performance reasons). Also, `amoplefttype` and `amoprighttype` must match the `oprleft` and `oprright` fields of the referenced `pg_operator` entry.


Table 1. `pg_catalog.pg_amop`

| column         | type     | references      | description                                                  |
| :------------- | :------- | :-------------- | :----------------------------------------------------------- |
|`oid`|	oid|		|Row identifier (hidden attribute; must be explicitly selected)
|`amopfamily`	|oid|	pg_opfamily.oid	|The operator family that this entry is for
|`amoplefttype`	|oid|	pg_type.oid	|Left-hand input data type of operator
|`amoprighttype`|	oid|	pg_type.oid|	Right-hand input data type of operator
|`amopstrategy`|	smallint|	|	Operator strategy number
|`amoppurpose`|	char	|	|Operator purpose, either s for search or o for ordering
|`amopopr`	|oid	|pg_operator.oid|	OID of the operator
|`amopmethod`|	oid	|pg_am.oid|	Index access method for the operator family
|`amopsortfamily`	|oid|	pg_opfamily.oid|	If an ordering operator, the B-tree operator family that this entry sorts according to; zero if a search operator