Distributed multi-version commitment ordering protocols for guaranteeing serializability during transaction processing
US5701480A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 14, 1993 |
| Grant date | Dec 23, 1997 |
| Priority date | — |
| Expiry date | Apr 14, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/466
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In a multi-version database, copies of prior committed versions (snapshots) are kept for access by the read-only transactions. The read-write transactions are selectively aborted to enforce an order of commitment of read-write transactions that is the same as an order of conflicts among the read-write transactions. In a preferred embodiment, the read-write transactions are serialized by maintaining and referencing a graph of conflicts among read-write transactions, and the read-only transactions are serialized by a timestamp mechanism for selection of the snapshots to be read. Each time that a read-write transaction is committed, the read-write transaction is assigned a unique timestamp that is used to timestamp all resources committed by the read-write transaction. Upon starting, each read-only transaction is also assigned a timestamp. Each read-only transaction reads only the latest committed versions of all resources, that are timestamped earlier than the timestamp of the read-only transaction. In a multiprocessing system, the timestamps are issued to global coordinators and distributed locally with atomic commit messages and global queries. Moreover, read-write transactions may…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.