System and method for a snapshot query during database recovery
US7146386B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Mar 29, 2004 |
| Grant date | Dec 5, 2006 |
| Priority date | — |
| Expiry date | Jan 6, 2025 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99953
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method of performing a snapshot query in a database undergoing recovery allows access to the database during rollback or undo operations. The method includes allowing the query to detect whether a redo lock is present on a data item and if so, waiting until subsequent rollback operations release the lock. If another user has placed an exclusive lock on a data item of the database, the query may continue by reading a version of the data item form the version store. In an embodiment where a mirror database is used for recovery, the constant redo operations have an associated version store. Upon failover to the mirror database, queries may begin during the undo phase of recovery by allowing a query to read the version store of redo operations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.