doubt on rollback segment

[ksarav]

Hi..
I'm new to dba.i've a doubt on rollback segment..oracle guru's kindly help me..
Here'z the doubt..
Any DML statements(insert,update,delete) made to any table in the database has a rollback entry..
But even a create tablespace command(which is a DDL) updates the sys owned table 'ts$' in data dictionary. why there are no rollback entries from 'create tablespace' command.??

kindly help..

Rgds,
Sarav

[pando]

who says there arent?

[hrishy]

Hi

rollback segmenst is used when i want to read consistency..

when you create a tablespace (DDL) ----raed consistency is not requied


when you do a ddl like this...

create table xyz
as
select * from emp --------------This requires read consistancy

hence eevnthough the second is a DDL it uses rollback because the select part has to eb done in read consistent mode..

when you do such opeartion ts$..they are logged in the redologs..not the rollback..

regards
Hrishy

[ksarav]

But pando..i've only studied that only dml statements will have rollback entries..thatz why you can rollback.
but,since ddl statements dont have a rollback entries,they cannot be rolled back.

Rgds,
sarav

[pando]

well

imagine you have to alter a 100000 millions of table, alter is DDL, what happens if during your alter the databse dies? you cannot rollback but Oracle can

[ksarav]

hey..ur answer sounds good.but can u give me a perfect answer.
tell me what happens when u give a ddl(create,alter,drop) and when you give an dml(insert,update,delete).
will there be rollback entries generated for the dml and ddl comands?

rgds,
sarav

[pando]

dont know what are you talking about

[adewri]

Originally posted by ksarav
hey..ur answer sounds good.but can u give me a perfect answer.
tell me what happens when u give a ddl(create,alter,drop) and when you give an dml(insert,update,delete).
will there be rollback entries generated for the dml and ddl comands?

rgds,
sarav

Read this...

http://asktom.oracle.com/pls/ask/f?p...2860243091362,

[ksarav]

thanks for that article..it was really great..

thanks adewri..

rgds,
sarav