Cause: Failed to allocate an extent of the required number of blocks for a rollback segment in the tablespace.
Action: Use ALTER TABLESPACE ADD DATAFILE statement to add one or more files to the tablespace indicated.
Sometimes the DBA does not know why Oracle is unable to allocate a new extent and for a quick solution he proceeds to add a new datafile. Not always is this solution is the best. Oracle has some views that help to determine which solution is better. This views are:
Indicate to DBA there is not free extent in the tablespace reported to support
the new extent. Consulting the view DBA_FREE_SPACE the DBA can know if really
the tablespace does not have space avaliable or the tablespace is fragmented and
a reorganization should be made. Remember that two contiguous extents are
considered two free spaces and both spaces can not be neither summarized nor
counted as one for free space contiguous.