There are two parameters: log_checkpoint_interval and log_checkpoint_timeout.

Log_checkpoint_interval is TARGET OS blocks in order for instance/crash recovery.
Log_checkpoint_timeout is TARGET time in order for instance./crash recovery.


Supposed you have 2000 blocks and 1500 blocks are full, which means the checkpoint can fire now, so that only next 500 blocks need to be redo to the datafile in case of recovery, which is what target means. If you have only 1400 full and checkpoint happen, then you need to redo 600 blocks.

But if you ask me whether checkpoint will fire at 500, 1000. That will be excellent question. I guess it will, but I never try it.

This two parameters are retired along with fast_start_io_target in Oracle9i, in favor of fast_start_MTTR_target.





[Edited by oca9i2002 on 10-21-2002 at 01:05 AM]