Method and system for fast recovery of a primary store database

摘要

The present invention provides an electronic data storage and processing system where non-persistent memory such as random access memory (RAM) stores a database with a first memory section storing semi-permanent data and a second memory section storing transient types of data. A third memory section in RAM may be used to buffer database transactions relating to the semi-permanent data stored in the first memory section of RAM. At periodic and appropriate checkpoint time intervals, the semi-permanent data currently stored in the first section of RAM are copied or "dumped" onto persistent (disk) memory. Only those database transactions that affect the semi-permanent data stored in the first section of RAM occurring after the most recent checkpoint "dump" are logged onto persistent memory. Database transactions affecting the transient type of data stored in the second portion of RAM are not logged. A recovery processor recovers from a system failure by reloading semi-permanent data from the persistent memory into the first section of RAM and executing the log. However, in one embodiment, the recovery processor may leave the data in the second section of RAM in the state in which that data exists after the system failure. Considerable time is saved by not logging transient database transactions or executing a log for those transactions when recovering from a system failure.