International Business Machines Corporation

Roger Lq Zheng

Garret Frederick Swart

Matthew Albert Huras

Gopi K Attaluri

Xun Xue

Michael Jeffrey Winer

Dale Murray McInnis

Piotr M Plachta

James Liam Finnie

Stewart L Palmer

Effi Ofar

In a shared data system comprising one or more primary nodes and a plurality of secondary nodes, global lock manager on a primary node manages locks for shared resources by exchanging an abstract lock state with local lock managers on the secondary nodes. The abstract lock state includes a particular representation of all of the applications on the nodes that are requesting or are granted locks. The exchange of these particular lock states instead of individual requests improves performance by increasing concurrency and reducing off-machine communication. A global deadlock detector on a node detects and resolves global deadlocks, in conjunction with local deadlock detectors on the secondary nodes.

Two-level management of locks on shared resources

A system and an associated method selectively process log files for enhancing performance of tablespace recovery by processing only those log files required, and for selecting which log file to process during recovery for both redo and rollback phases of recovery. The system and method skip the processing of log files that do not contain records of interest for the tablespace being recovered and determines whether a log file contains anything that needs to be played, in particular for the recovery of a subsystem in the database, such as a tablespace. Pre processing of the log files is not done, rather including tablespace ID correlated with log file ID information is collected while the log files are created. The cross-correlated information is used during tablespace recovery to selectively determine which of the log files to process. Some log files may be skipped in cases where not all of the database system is being recovered. A sub set of the database can be recovered, such as a tablespace, and which log files to process is determined based on a lock instruction.

System and method for discriminatory replaying of log files during tablespace recovery in a database management system

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Richmond Hill, Canada

Roger Lq Zheng