redbookcover.gif (13955 bytes) Readings in Database Systems, 3rd Edition

Stonebraker & Hellerstein, eds.

Checkpointing

Periodically, the DBMS creates a checkpoint, in order to minimize the time taken to recover in the event of a system crash. Write to log:

begin_checkpoint record: Indicates when chkpt began.
end_checkpoint record: Contains current Xact table and dirty page table. This is a `fuzzy checkpoint’:
Other Xacts continue to run; so these tables accurate only as of the time of the begin_checkpoint record.
No attempt to force dirty pages to disk; effectiveness of checkpoint limited by oldest unwritten change to a dirty page. (So it’s a good idea to periodically flush dirty pages to disk!)
Store LSN of chkpt record in a safe place (master record).

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1998, Joseph M. Hellerstein.  Last modified 08/17/98.
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