Method for deallocating a log in database systems
US5832508A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 14, 1996 |
| Grant date | Nov 3, 1998 |
| Priority date | — |
| Expiry date | Nov 14, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F11/1466
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A SQL database server system having an enhanced logging system is described. The logging system implements a "private log cache" (PLC) for reducing the contention on the system's "log" resource (which is protected by a log semaphore). An area of memory private to a user's task is set aside as a PLC--a cache where log records are built and stored before being posted to the log. Each PLC may hold multiple log records for a single transaction before they are flushed to the log (page chain) through the log semaphore. When a transaction commits or the memory fills with log records, the PLC associated with the transaction is flushed to the log. Also described is improved log deallocation methodology provided by the system which alleviates the needs to read each of the log pages to be deallocated, as was conventionally required. The operation to do the deallocation occurs at the allocation page, not at the individual pages (which are to be deallocated). In accordance with this method, the system writes a log record which includes the first page and the last page of the run (i.e., the number of those pages). The system need not, however, read any of the pages of the run, other than the fir…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.