Re: What is the difference with Redo log, Archivelog, Undo ?

From: Charles Hooper <hooperc2000_at_yahoo.com>
Date: 20 Mar 2007 03:43:21 -0700
Message-ID: <1174387401.346272.11850@y80g2000hsf.googlegroups.com>

On Mar 20, 6:22 am, "robertchen..._at_gmail.com" <robertchen..._at_gmail.com> wrote:
> What is the difference with Redo log, Archivelog, Undo ?
>
> I think Redo log is the same with archivelog?

The most complete answers can be found here: http://www.oracle.com/pls/db102/search?word=redo+undo&partno=

In short, the redo log contains undo information also. When a redo log becomes full, it is eligible to become an archived redo log, and stored in a different location (if the database is set up IN ARCHIVELOG MODE. Undo is used to roll back transactions and provide read consistency, while redo is used to roll forward transactions in the event of problems.

SELECT
LOG_MODE
FROM
V$DATABASE; Charles Hooper
PC Support Specialist
K&M Machine-Fabricating, Inc. Received on Tue Mar 20 2007 - 05:43:21 CDT