Optimize Space

Use this page to optimize storage space. Compress tables, indexes, and fragments, consolidate free space (repack), return free space to the dbspace (shrink), merge extents (defragment), or remove in-place alter operations. You can also uncompress tables and table fragments.

Specify the actions to take for the selected tables, indexes, and fragments.

Compress

Select this option to build a compression dictionary and compress the tables, indexes, and fragments that are not compressed. Tables and table fragments with fewer than 2000 rows are automatically compressed when 2000 or more rows are loaded. Specify whether to compress the simple large objects (TEXT and BYTE data types) that are stored in partitions in the same dbspace. A separate compression dictionary is built for each compressed, non-fragmented table and non-fragmented index partition, and for each individual compressed table fragment and index fragment. For an index or index fragment, the table that the index or index fragment is based on must contain at least 2000 rows. Detached B-tree indexes, including unique, duplicate, and forest of trees indexes, can be compressed.

Uncompress

Select this option to uncompress the tables and table fragments that are compressed. If you select this option, tables and table fragments that have fewer than 2000 rows will no longer be automatically compressed when 2000 or more rows are loaded. Uncompressing also stops compression of insert and update operations, deactivates the compression dictionary, and allocates new pages for rows that do not fit on their original pages. Indexes cannot be uncompressed.

Offline

Select this option to place an exclusive lock on the tables and table fragments during the operation to prevent access to the data.

Repack

Select this option to consolidate free space in the tables, indexes, and fragments. You can consolidate free space when you compress the tables, indexes, and fragments, or you can consolidate free space as a separate action.

Offline

Select this option to place an exclusive lock on the tables, indexes, and fragments during the operation to prevent access to the data. You cannot compress and repack as one operation offline. To repack offline, run the compression task, and then run the repack task with the offline option.

Shrink

Select this option to return any free space in the tables, indexes, and fragments to the dbspace. You can return free space to the dbspace when you compress or repack, or you can return free space to the dbspace as a separate action. Returning free space reduces the total size of the table, indexes, and fragments.

Defragment extents

Select this option to merge extents in the tables, indexes, and fragments to reduce the number of extents.

Remove outstanding in-place alter operations

Select this option to remove in-place alters from selected tables. This option removes data pages that have outdated definitions for the selected tables.