Patent ID: 6795898
Filing Date: 2004-09-21
Classification: G06F,Y10S

Abstract:
An apparatus for virtual memory mapping and transaction management for a database system, comprising:at least one permanent storage device for storing data in at least one database, a plurality of client computers each having a cache memory for storing data and a processing unit, the processing unit including means for requesting data from said at least one database and means for transferring data between the at least one permanent storage device and the cache memory, means, responsive to a request for data from a database from the means for requesting of a first client computer, for detecting if requested data is in the cache memory of a second client computer and has a cached state such that access to the data by the first client computer is not permitted, means, responsive to a detection by said means for detecting that access to the data by the first client computer is not permitted, for instructing said second client computer to change the cached state of the data, and means for transferring said requested data to the first client computer after the second client computer characterizes the cached state of the data, wherein a request for data is one of a read request and a write request, wherein said at least one database is divided into segments, each containing one or more pages and wherein said means for transferring said requested data transfers a page containing the requested data, wherein the apparatus further comprises: means, responsive to a transfer of a page in response to a read request for the page, for encaching the page for read and for locking the page for read at the first client computer, and means, responsive to a transfer of a page in response to a write request for the page for encaching the page for write and for locking the page for write at the first client computer.