Patent ID: 8423528

Claim:
A computer program product comprising a computer-readable storage medium tangibly storing instructions that, when executed by a data processing apparatus that comprises a programmable processor, cause the data processing apparatus to perform operations comprising: first compressing data stored in a first index, the compressing comprising using a first dictionary comprising a global value identifier for dictionary-based compression of the first index; receiving a request for a change of first data of a first record in the first index to second data of the first record; storing a second record in a second index, the second record representing the change of the first data of the first record; second compressing data stored in the second index, the second compressing comprising using a second dictionary comprising a local value identifier for dictionary-based compression of the second index, the local value identifier representing the change to the first data of the first record and an association of the local value identifier with the change of the first data of the first record, the local value identifier differing from the global value identifier for the first record; generating an association between the global value identifier and the local value identifier in the second dictionary, the association mapping the local identifier to the global identifier to preserve referential correctness; adding the association to an association column in the second index; and translating a received search request to a single, consistent value identifier scheme using at least the association column.