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.

**Table 1** PG_OPCLASS columns
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 an index, or zero if same as opcintype