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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 whichever ones accept the column's data type as their left-hand input.

Table 1 PG_OPCLASS columns

Name Type Reference Description
oid oid - Row identifier (hidden attribute, which must be specified)
opcmethod oid PG_AM.oid Index access method operator class served by an operator class
opcname name - Name of the operator class
opcnamespace oid PG_NAMESPACE.oid Namespace of the operator class
opcowner oid PG_AUTHID.oid Owner of the operator class
opcfamily oid PG_OPFAMILY.oid Operator family containing the operator class
opcintype oid PG_TYPE.oid Data type that the operator class indexes
opcdefault boolean - The value is true if this operator class is the default for opcintype.
opckeytype oid PG_TYPE.oid 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.

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