A database with many noncontiguous, small blocks of free space is said to be fragmented. A fragmented database should be reorganized to make space available in contiguous, larger blocks. You can reduce fragmentation by performing a full database export and import as follows:

 1 ) Do a full database export (FULL=y) to back up the entire database. 
 2 ) Shut down the Oracle database server after all users are logged off. 
 3 ) Delete the database. See your Oracle operating system-specific documentation for information on how to delete a database. 
 4 ) Re-create the database using the CREATE DATABASE statement. 
 5 ) Do a full database import (FULL=y) to restore the entire database.