Usage of Checkpoint Files

TimesTen creates two checkpoint files for each database, named dsname.ds0 and dsname.ds1, where dsname is the database path name and file name prefix specified in the database DSN.

During a checkpoint operation, TimesTen determines which checkpoint file contains the most recent consistent image and then writes the next in-memory image of the database to the other file. Thus, the two files contain the two most recent database images.

In TimesTen, the database maintains one set of checkpoint and transaction log files.

TimesTen uses the most recent checkpoint file and transaction log files to recover the database to its most recent transaction-consistent state after a database shutdown or system failure. (The most recent transaction log files are those written since the checkpoint was done.) If any errors occur during this process, or if the more recent checkpoint image is incomplete, then recovery restarts using the other checkpoint file. See Transaction Logging.