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AdministeringIn addition to administering the database server, you can tune performance, replicate data, and archive data.
System administrationThese topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning HCL OneDB™ database servers.
Performance GuideThe HCL OneDB™ Performance Guide describes how to configure and operate your HCL OneDB™ database server to improve overall system throughput and to improve the performance of SQL queries.
Table performance considerationsSome performance issues are associated with unfragmented tables and table fragments.
Managing extentsAs you add rows to a table, the database server allocates disk space in units called extents. Each extent is a block of physically contiguous pages from the dbspace. Even when the dbspace includes more than one chunk, each extent is allocated entirely within a single chunk, so that it remains contiguous.
Reclaiming unused space within an extentAfter the database server allocates disk space to a tblspace as part of an extent, that space remains dedicated to the tblspace. Even if all extent pages become empty after you delete data, the disk space remains unavailable for use by other tables unless you reclaim the space.
Reclaiming space in an empty extent with ALTER INDEXIf the table with the empty extents includes an index, you can run the ALTER INDEX statement with the TO CLUSTER clause. Clustering an index rebuilds the table in a different location within the dbspace.

Reclaiming space in an empty extent with ALTER INDEX

If the table with the empty extents includes an index, you can run the ALTER INDEX statement with the TO CLUSTER clause. Clustering an index rebuilds the table in a different location within the dbspace.

When you run the ALTER INDEX statement with the TO CLUSTER clause, all of the extents associated with the previous version of the table are released. Also, the newly built version of the table has no empty extents.