Asynchronous replica management in shared nothing architectures
US5440727A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 15, 1994 |
| Grant date | Aug 8, 1995 |
| Priority date | — |
| Expiry date | Jul 15, 2014 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99953
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In a partitioned database system of the Shared Nothing type, one or more secondary replicas of each partition are maintained by spooling (i.e., asynchronously sending) modified (usually called dirty) pages from the primary replica to the secondary replica(s) rather than by using a synchronous page update or by sending log entries instead of entire pages. A Write-Ahead Log protocol is used so that a dirty page is not forced to non-volatile storage until a log record of the modification is created and written to non-volatile storage. Replica updating does not delay the committing of transactions because replica updating is done asynchronously with respect to transaction processing. Since dirty pages are sent rather than only log entries, disk accesses and processing at the secondary replica(s) arising from the maintaining of the replicas are minimized as well. Only one centrally accessible log is maintained for all replicas of the same partition.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.