An OR strategy uses a set of index scans to limit the scan with each of the OR terms, then passes the resulting RIDs through a UnionDistinct operator to get, with a RidJoin from the table, the tuples corresponding to the unique RIDs.
The m_scan (multi-scan) abstract plan operator forces index union, hence the OR strategy:
select * from t1 where c11 > 10 or c12 > 100 plan “(m_scan t1)”
