Point-in-time database recovery using log holes
AssigneeSap SE
InventorIvan Schreter
Life of this patent
Estimating the term…
Abstract
A first plurality of log segments are generated in a data storage application. The log segments are sequentially positioned within a log area and at least one of the log segments contains log hole information identifying a portion of log to skip during replay of the log. Thereafter, a portion of log segments are replayed up to a specified position while skipping at least one portion of the log prior to the specified position that is identified by the at least one log hole. Related apparatus, systems, techniques and articles are also described.
Claims20
A non-transitory computer program product storing instructions that, when executed by at least one programmable processor, cause the at least one programmable processor to perform operations comprising:
- generating a first plurality of log segments of a log in a data storage application, the log segments being sequentially positioned within a log area, at least one of the log segments containing log hole information indicating which portions of the log were skipped during point-in-time recovery;
- replaying a portion of the log segments up to a specified position, the replaying skipping at least one portion of the log prior to the specified position that is indicated by the log hole information as having been skipped during point-in-time recovery;
- and
- writing subsequent log segments at positions subsequent to the at least one portion skipped ruing the replaying, wherein each subsequent log segment comprises a header describing the log information.
A method comprising:
- generating a first plurality of log segments in a data storage application, the log segments being sequentially positioned within a log area, at least one of the log segments containing log hole information indicating which portions of the log were skipped during point-in-time recovery;
- replaying a portion of the log segments up to a specified position, the replaying skipping at least one portion of log prior to the specified position that is indicated by the log hole information as having been skipped during point-in-time recovery;
- and
- writing subsequent log segments at positions subsequent to the at least one portion skipped ruing the replaying, wherein each subsequent log segment comprises a header describing the log information.
A system comprising:
- at least one programmable processor;
- and
- memory coupled to the at least one programmable processor, the memory storing instructions, which when executed, cause the at least one programmable processor to perform operations comprising:
- generating a first plurality of log segments in a data storage application, the log segments being sequentially positioned within a log area, at least one of the log segments comprising log hole information indicating which portions of the log were skipped during point-in-time recovery in a header portion of the corresponding log segment;
- replaying a portion of the log segments up to a specified position, the replaying skipping at least one portion of log prior to the specified position that indicated by the log hole information as having been skipped during point-in-time recovery;
- and
- writing subsequent log segments at positions subsequent to the at least one portion skipped ruing the replaying, wherein each subsequent log segment comprises a header describing the log information;
- wherein:
- at least one log segment was generated containing or subsequent to the specified recovery end position,
- a first log segment generated after starting or restarting the data storage application identifies a corresponding log hole including at least portion of one log segment containing or generated subsequent to the specified recovery end position, and
- new log segments are created when a prior log segment becomes full and such new created log segments do not contain the log hole information.
Dependencies are inferred from the claim text.