Oracle Corporation
QUERYING ON HYBRID FORMATS AND STORAGES

Abstract:

Techniques are described for querying on hybrid formats and storages by a DBMS to leverage faster mirror format (MF) data and completeness of persistent format (PF) data. In an embodiment, the DBMS receives a query that specifies both in-memory and disk-only columns. The DBMS identifies that a scan-based operation is referencing an in-memory column stored within both MF and PF data. The DBMS may initiate performing the operation on the in-memory column on one of the formats of data. While doing so, the DBMS may determine that the actual improvement metric for the operation on the selected format data is not achieving the desired improvement. If so, the DBMS may dynamically switch the performing of the scan-based operation to the other format of the same data.