Identifying and Reclaiming Unused Space
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Reclaiming Unused Space

After you determine that a table and its indexes have a significant amount of unused space, use the ALTER TABLE command with the COMPRESS clause to reclaim that space.

Reclaiming space returns it to the operating system.

For example, after you have identified that the FlightAvailability table and its related indexes have a significant amount of unused space, you could reclaim that space with the following command:

ALTER TABLE FlightAvailability COMPRESS

By default, the ALTER TABLE COMPRESS command instructs Cloudscape to compress the table and its related indexes concurrently, which may use a lot of temporary disk space and memory. When you add the keyword SEQUENTIAL to the command, Cloudscape compresses the table and indexes sequentially, one at a time. Sequential compression uses less memory and disk space but is slower. For example:

ALTER TABLE FlightAvailability COMPRESS SEQUENTIAL

For more information about this command, see the Cloudscape Reference Manual.