ONCHECK & checkpoints

IDS 12 AIX 7 Can this command cause large checkpoints ? oncheck -cDI eppix:"informix".my_table my_table = 455 million rows

well it could. oncheck cDI does a very comprehensive check (matching table rowids to the index etc.) and depending on what had to be flushed to disk during the checkpoint may have resulted in contention over i/o resources. This assumes your Informix instance is configured properly. you can monitor with sar -d and see how pegged the hdisks are while the oncheck is running. Also check what the size of the avgque is and compare that to your queue depths setting (the default on aix is 3 but can be increased dynamically). The avgqueu should not exceed the queue depths settings otherwise an OS overhead is incurred in managing i/o. Mark

Thank you. Ok, back to business - we have a few suspect indexes. So we decided to rebuild them (drop and create), rather than run onchecks on them. The tables (and thus the indexes) are very big. Thank you for your response. Dirk