Rollback segment

[bhattnirav]

I have created rollback segment with following command

CREATE ROLLBACK SEGMENT RB15 TABLESPACE RBSDATAA STORAGE (INITIAL 3M NEXT 3M OPTIMAL 70M MINEXTENTS 20);

when i query dba_rollback_segments

query shows me AS

INITIAL_EXTENT 62914560
NEXT_EXTENT null
MIN_EXTENTS 1
MAX_EXTENTS 32765

Query shows different storage value.

what is the reason?

[Bore]

See if tablespace RBSDATAA is locally managed
select extent_management from dba_tablespaces
where tablespace_name='RBSDATAA'

[bhattnirav]

Thanks for your reply.

Yes, RBSDATAA is locally managed tablespace

[Bore]

Well, when you use locally managed tablespace, the STORAGE clause is ignored. The extent size is either equal to the "granule" (in case if the tablespace is with uniform extent size) or is authomatically determined by Oracle (in case if extent pollicy is authomatic)
The storage clause however does not causes any error, for backward compatibility.
Only the initial extent and the min extents clauses are in force, meaning that at the segment creation are allocated as many extents, as specified in the min extents clause or to reach the initial extent size.
Generally, isnce you use locally managed tablespaces, I supose you use 9i or later and I would recommend using authomatic undo management feature

Regards

[tamilselvan]

Generally, isnce you use locally managed tablespaces, I supose you use 9i or later and I would recommend using authomatic undo management feature

Not necessary. If you can manage the tablespace with UNIFORM SIZE, then do it. Lot of fine tuning opportunities is lost if you ASSM.