System and method for utilizing compression in database caches to facilitate access to database information
A system and method are disclosed for utilizing compression in database caches to facilitate access to database information. In contrast with applying compression to the database that is stored on disk, the present invention achieves performance advantages by using compression within the main memory database cache used by a database management system to manage data transfers to and from a physical database file stored on a storage system or stored on a networked attached device or node. The disclosed system and method thereby provide a significant technical advantage by increasing the effective database cache size. And this effective increase in database cache size can greatly enhance the operations-per-second capability of a database management system by reducing unnecessary disk or network accesses thereby reducing data access times.
1. A system for managing access to database information, comprising:
a first data storage device storing a database, the first data storage device comprising a storage device coupled to a server system;
a second data storage device storing a local database cache, wherein at least a portion of the local database cache comprises a compressed cache portion and an uncompressed cache portion where the uncompressed cache portion is less than the full local database cache, wherein the second data storage device comprises a local storage device coupled to a client system in a client-server environment, wherein the local database cache is utilized by the client system, and wherein the entire local database cache comprises compressed data and there is no uncompressed data; and
a database management system controlling data transfers between the database stored by the first data storage device and the local database cache stored by the second data storage device and between the compressed portion of the local database cache and the uncompressed portion of the local database cache, if any, to manage accesses to database information by the client system, wherein the database management system comprises the client system.
2. The system of claim 1 , wherein the first data storage device comprises a disk drive.
3. The system of claim 1 , wherein the second data storage device comprises memory within a computer system.
4. The system of claim 3 , wherein the memory is configured to store database cache information in pages.
5. The system of claim 4 , wherein each database cache page stored within memory is configured to include a flag indicating whether or not the page comprises compressed data.
6. The system of claim 1 , wherein the server system also has a database cache having a compressed portion and an uncompressed portion.
7. The system of claim 1 , wherein a plurality of client systems are coupled to the server system in a client-server environment and wherein each client system has a local database cache having a compressed portion and an uncompressed portion.
8. A database management system for managing access to database information in a client-server environment comprising:
a plurality of client systems, the client systems configured to access accessing information in a database;
a server system coupled to the client systems through a network, the server system managing transfers of information between the client systems and the database;
a first data storage device coupled to the server system and storing the database; and
a local data storage device coupled to each client system and storing a local database cache, wherein the local database cache comprises a compressed cache portion and an uncompressed cache portion where the uncompressed cache portion is less than the full local database cache, and wherein the entire local database cache comprises compressed data and there is no uncompressed data;
wherein the server system controls data transfers between the database and the local database caches for the client systems; and
wherein each of the clients systems controls data transfers between the compressed portion of the local database cache and the uncompressed portion of the local database cache, if any, to manage accesses to database information by the client system.
9. The database management system of claim 8 , wherein the first data storage device comprises a disk drive.
10. The database management system of claim 8 , wherein the second data storage device comprises memory within a computer system.
11. The database management system of claim 8 , wherein the server system is also configured to manage a database cache having a compressed portion and an uncompressed portion.
12. A method for managing access to database information, comprising:
storing a database in a first data storage device, the first data storage device comprising a remote storage device coupled to a server system;
storing a local database cache in a second data storage device, wherein the local database cache comprises a compressed cache portion and an uncompressed cache portion where the uncompressed cache portion is less than the full local database cache, wherein the second data storage device comprises a local storage device coupled to a client system in a client-server environment, and wherein the local database cache is utilized by the client system;
storing the entire local database cache as compressed data such that there is no uncompressed data;
controlling data transfers among the database and the local database caches for the client system; and
controlling with the client system the compressed portion of the local database cache and the uncompressed portion of the local database cache, if any, to manage accesses to database information by the client system.
13. The method of claim 12 , wherein the first data storage device comprises a disk drive.
14. The method of claim 12 , wherein the second data storage device comprises memory within a computer system.
15. The method of claim 14 , configuring the memory to store database cache information in pages.
16. The method of claim 15 , further comprising utilizing for each stored database cache page a flag within the page to indicate whether or not the page comprises compressed data.
17. The method of claim 12 , wherein, the server system also manages a database cache having a compressed portion and an uncompressed portion.