Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
2001-06-22
2004-04-27
Le, Uyen (Department: 2171)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000, C711S152000
Reexamination Certificate
active
06728709
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to database management systems, and more particularly to lock management for partitioned databases.
BACKGROUND OF THE INVENTION
A database is partitioned for administrative and performance purposes. A partition is defined in terms of a range of keys, either primary or secondary, to records in a table. Partitions allow a database administrator (DBA) to add, delete, or change information for a range of records in a table. For example, if some data within a partition of the table is no longer valid, the DBA can remove the partition that contains invalid data and then restore the valid data to the partition. Without partitions, the DBA would have to remove the entire table and restore the valid data, thereby making the entire database inaccessible to users. The partitions allow a user to continue to access some portions of a table while another portion of it has been removed for maintenance.
In support of concurrent access to a database, data locks are used to protect the data in individual rows, partitions, or database tables. Partition-level locking allows a user to lock a particular partition without impacting other users' access to other partitions. Some databases include many partitions for administrative convenience and for promoting concurrent access. However, some database applications and operations require locking every partition in the database, which is known as a “table lock.”
In a database having many partitions, frequent table locks may negatively impact system performance. Since every partition must be checked and locked to issue a table lock, the time required to process a table lock will depend in part on the number of partitions. Furthermore, frequent table locks will multiply the inefficiency.
A method and apparatus that addresses the aforementioned problems, as well as other related problems, are therefore desirable.
SUMMARY OF THE INVENTION
In various embodiments, the invention provides a method and apparatus for locking a database table having a plurality of partitions. Separate lock status codes are maintained for both the entire database table and for the partitions of the database table. The partition locks do not need to be updated when a lock is granted for the database table since a separate table lock status code is maintained. The separate table lock status code improves database application performance and simplifies programming of explicit lock operations.
The above summary of the present invention is not intended to describe each disclosed embodiment of the present invention. The figures and detailed description that follow provide additional example embodiments and aspects of the present invention.
REFERENCES:
patent: 4716528 (1987-12-01), Crus et al.
patent: 5448727 (1995-09-01), Annevelink
patent: 5596754 (1997-01-01), Lomet
patent: 5717919 (1998-02-01), Kodavalla et al.
patent: 6041384 (2000-03-01), Waddington et al.
patent: 6343296 (2002-01-01), Lakhamraju et al.
patent: 6411964 (2002-06-01), Iyer et al.
patent: 6438562 (2002-08-01), Gupta et al.
Hoevel et al “File partitioning as a means to reduce lock contention in a multiprocessor environment”, IEEE 1992, pp. 211-217.*
Alexander Thomasian, “A performance comparison of locking methods with limited wait depth”, IEEE 1997, pp. 421-434.*
Thekkath et al, “Frangipani: a scalable distributed file system”, ACM 1997, pp. 224-237.*
Kim et al, “MIDAS: design philosophy and internals”, IEEE 1992, pp. 0132-0139.
Frauendienst Don W.
Plasek James M.
Rust John C.
Crawford & Maunu PLLC
Johnson Charles A.
Le Uyen
Starr Mark T.
Unisys Corporation
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