51.33. pg_opclass
The catalog 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 whichever ones accept the column's data type as their left-hand input.
Operator classes are described at length in Section 37.14.
Table 51.33. pg_opclass
Columns
oid
oid
Row identifier (hidden attribute; must be explicitly selected)
opcname
name
Name of this operator class
opcdefault
bool
True if this operator class is the default for opcintype
An operator class's opcmethod
must match the opfmethod
of its containing operator family. Also, there must be no more than one pg_opclass
row having opcdefault
true for any given combination of opcmethod
and opcintype
.