Re: [beginner] Why Oracle needs both redo logs and rollbacksegments ?

From: Jan Gelbrich <j_gelbrich_at_westfalen-blatt.de>
Date: Thu, 5 Jun 2003 10:13:48 +0200
Message-ID: <bbmu76$b9886$1@ID-152732.news.dfncis.de>

"F.Marchioni" <NOSPAMfmarchioni_at_libero.it> schrieb im Newsbeitrag news:AoCDa.61980$Ny5.1875602_at_twister2.libero.it...
> Hi all,
> please forgive the beginner's question, I'm just studying something
> about Oracle architecture. I'm just wondering why Oracle needs
> both redo logs and rollback segments to keep track of transactions...
> reading the manual they seem to pursue a quite similar job....anybody
> can give me an explanation ?
> Thanks a lot
> Francesco
>
>

Hi Francesco,

redo logs and rollback segments have _opposite_ pursposes:

redo log: _re_do, e.g. in the case of a disk crash (that is why redo logs should be mirrored on different disks)
rollback: _un_do transactions that You do not want to commit;

Do not worry; when I was a newbee, I was confused just the same ;-)

hth, Jan Received on Thu Jun 05 2003 - 03:13:48 CDT