SAP SE
Multi-level storage architecture

Abstract:

Deleting a data record from the second level storage or main store is disclosed. A look-up is performed for the data record in the first level storage, where the data record is defined by a row identifier. If the row identifier is found in the first level storage, a look-up is performed for an updated row identifier representing an update of the data record in the second level storage and the main store, the update of the data record being defined by an updated row identifier. If the updated row identifier is found in the second level storage, an undo log is generated from the first level storage to invalidate a row identifier of the row identifier. A flag is generated representing an invalid updated row identifier, and a redo log is generated to restore the data record in the first level storage.