The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 09, 2002
Filed:
Dec. 16, 1998
David G. Campbell, Redmond, WA (US);
Microsoft Corporation, Redmond, WA (US);
Abstract
A multilevel data locking mechanism is described. The mechanism determines the cost of multiple granularities of locks for a query prior to initiating a transaction. Locking selection is performed by a lock manager, and is based on row, page and table granularities. An SQL server provides access to a database comprising rows of data arranged in tables. A table has multiple rows per page, and multiple pages per table. Characteristics of the database schema and query are considered in determining which granularity will result in the lowest cost. These factors include the number of rows per page, the number of rows per index scan, the isolation level per scan, an update factor which is related to how long modified rows are held, the memory load on the system, the cost of concurrency which is based on the number of rows per page and pages per table, and the number of active scans currently on the table. The proper granularity is determined at run time to ensure that the current state of the system is considered.