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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 Informix® database servers.
Performance GuideThe Informix® Performance Guide describes how to configure and operate your HCL Informix® 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.
Releasing space in an empty extent with ALTER FRAGMENT You can use the ALTER FRAGMENT statement to rebuild a table. When you run this statement, it releases space within the extents that were allocated to that table.

Releasing space in an empty extent with ALTER FRAGMENT

You can use the ALTER FRAGMENT statement to rebuild a table. When you run this statement, it releases space within the extents that were allocated to that table.

For more information about the syntax of the ALTER FRAGMENT statement, see the Informix® Guide to SQL: Syntax.

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