Patent ID: 7979408
Filing Date: 2011-07-12
Classification: G06F

Abstract:
1. A method that facilitates synchronization of concurrent database transactions in a database management system that manages a database having a database data page that provides sub-page row storage space, the database management system further managing a plurality of concurrent database transactions, each of the concurrent database transactions requiring a modification of the database data page, the method comprising: creating a copy of the database data page for each of the concurrent database transactions, each of the concurrent database transactions storing its respective copy of the database data page in a separate reserved space to facilitate modifying the database data page; assigning an exclusive row level lock on a first row of the database data page to one of the concurrent database transactions when the one of the concurrent database transactions requests to modify the first row, the exclusive lock permits the one of the concurrent database transactions to modify a copy of the first row in its respective copy of the database data page while restricting others of the concurrent database transactions from modifying corresponding copies of the first row in their respective copies of the database data page, but allows the others of the concurrent database transactions to modify other rows; assigning an allocation lock on the database data page to the one of the concurrent database transactions when the one of the concurrent database transactions seeks additional space to modify the database data page, the allocation lock permits the one of the concurrent database transactions to acquire additional space on the database data page and to use the additional space in its respective copy of the database data page and allows the others of the concurrent database transactions that do not require additional space on the database data page to effect modifications to their respective copies of the database data page, but prevents the others of the concurrent database transactions from acquiring additional space on the database data page; each of the concurrent database transactions modifying its respective copy of the database data page using row level operations to facilitate modifying the database data page; tracking space availability for the database data page over the concurrent database transactions, the concurrent database transactions operating on respective copies of the database data page; ensuring that the concurrent database transactions do not consume all of storage space on the database data page based in part on the tracked space availability; and enforcing a set of conditions on any transaction that operates on the database data page, such that reorganization of data around the database data page at a commit stage of the concurrent database transactions is mitigated while merging of various copies of the database data page during the commit operation.