PG_OPCLASS
PG_OPCLASS defines index access method operator classes.
Each operator class defines semantics for index columns of a particular data type and a particular index access method. An operator class essentially specifies that a particular operator family is applicable to a particular indexable column data type. The set of operators from the family that are actually usable with the indexed column are data types that accept the left-hand column.
| Name | Type | Reference | Description |
|---|---|---|---|
| OID | OID | - | Row identifier (hidden attribute, which must be specified) |
| opcmethod | OID | OID in PG_AM | Index access method operator class served by an operator class |
| opcname | name | - | Name of the operator class |
| opcnamespace | OID | OID in PG_NAMESPACE | Namespace of the operator class |
| opcowner | OID | OID in PG_AUTHID | Owner of the operator class |
| opcfamily | OID | OID in PG_OPFAMILY | Operator family containing the operator class |
| opcintype | OID | OID in PG_TYPE | Data type that the operator class indexes |
| opcdefault | Boolean | - | The value is t (true) if the operator class is the default for opcintype. Otherwise, the value is f (false). |
| opckeytype | OID | OID in PG_TYPE | Type of data stored in index, or zero if same as opcintype |
An operator class's opcmethod must match the opfmethod of its containing operator family.
