RIDSCN

RIDSCN

Operator name: RIDSCN

Represents: The scan of a list of row identifiers (RIDs) obtained from one or more indexes.

This operator is considered by the optimizer when:

• Predicates are connected by OR keywords, or there is an IN predicate. A technique called index ORing can be used, which combines results from multiple index accesses on the same table.

• It is beneficial to use list prefetch for a single index access, since sorting the row identifiers before accessing the base rows makes the I/O more efficient.