As aggregate storage outline files (.otl files) are changed (for example, when members are added or deleted), they may increase in size. By compacting such files, you can remove the records of deleted members and reduce the outline file size. After the outline file is compacted, the file continues to grow as before, when members are added or deleted.
Compacting the outline file causes the database to restructure the outline. Compacting the outline does not cause the database to clear the data.
When a member is deleted from the outline, the corresponding record of that member in the outline file is marked as deleted, but the record remains in the outline file. Compacting the outline file does not remove the records of deleted members.
Note:
You can only compact aggregate storage database outlines. The process of compacting an outline can take place only when no other users or processes are actively using the database
To compact an aggregate storage database outline: