Click here to view and discuss this page in DocCommentXchange. In the future, you will be sent there automatically.

SQL Anywhere 10.0.1 » SQL Anywhere Server - Database Administration » Backup and Data Recovery » Backup and recovery internals

The automatic recovery process Next Page

How the database server decides when to checkpoint

The priority of writing dirty pages to the disk increases as the time and the amount of work since the last checkpoint grows. The priority is determined by the following factors:

The checkpoint and recovery urgencies are important only if the server does not have enough idle time to write dirty pages.

Frequent checkpoints make recovery quicker, but also create work for the server writing out dirty pages.

There are two database options that allow you to control the frequency of checkpoints. checkpoint_time controls the maximum desired time between checkpoints and recovery_time controls the maximum desired time for recovery in the event of system failure.

If, because of other activity in the database, the number of dirty pages falls to zero, and if the urgency is 50% or more, then a checkpoint takes place automatically since it is a convenient time.

Both the checkpoint urgency and recovery urgency values increase in value until the checkpoint occurs, at which point they drop to zero. They do not decrease otherwise.

See also