Free Space Recovery

Database recovery occurs when you load an application that has just crashed or terminated abnormally. Essbase does not perform free space recovery automatically, because it is the most expensive part of database recovery. You must either trigger free space recovery explicitly or change the default setting so that Essbase will recover free space automatically.

All database functions run normally whether you recover free space or not. When you recover free space, you can reuse disk space marked as free in the data files. Keep in mind that free space recovery is time-consuming, so you might delay it until a better time.

You should, however, perform free space recovery as soon as possible to take advantage of the free space in the data files and to ensure that the database has not been corrupted. Also, if a database crashes repeatedly, and you do not run free space recovery, data files can become unnecessarily large.

To trigger free space recovery, use the MaxL alter database command. For example:

alter database DBS-NAME recover freespace

See the Technical Reference.

To change the default behavior for free space recovery, change the DELAYEDRECOVERY configuration setting to FALSE. See the “Configuration Settings” section of the Technical Reference.

To get information about free space recovery, use the GETDBSTATS command. GETDBSTATS provides the following information about free space recovery:

Free Space is Recoverable                 : true/false
Estimated Bytes of Recoverable Free Space : nnn

Note:

If free space is recoverable, the block counters are estimates and do not necessarily match the number of existing blocks.