If data has been archived or simply deleted and the associated tables were accessed via an index, the index should be reorganized. Deleting table entries leaves holes in the table which are still indexed. Reorganization can shorten the access paths, reducing response times.

If your database uses a cost-based optimizer, you must choose Update Statistics to recalculate the access paths.

Whether you should reorganize the tablespace depends on the reason for archiving.

• Do you expect a lot of new data for the archived tables?
  If so, you should not reorganize.
  If, on the other hand, you archived data that is no longer needed in the system and the table is otherwise rarely changed, you should reorganize.

• Do you want to make space for other tables?
  If so, you should reorganize the tablespaces of both the tables and the indices.

The procedure is described in the Basis document Database Administration (SAPDBA, for Oracle and Informix databases) or ABAP/4 Dictionary, section Tablespaces and Extents (database-independent parameterization for ADABAS).