Re: Bookish Questions need Ideas

arijitchatterjee123_at_yahoo.co.in (Arijit Chatterjee) wrote in message news:<ea01504d.0409300314.43ea03f7_at_posting.google.com>...
> Dear Faculties..
> Again some basic question I am asking regarding
> Rolllback Segment and Redo Log.Yes this time after
> reading from many resources.But last time also I read that
> but why multiple files are using that was the main
> question.
>
> Point1 : A rollback segment records the old values of data
> that was changed by each transaction (whether or not committed).
>

http://www.oracle.com/pls/db92/db92.to_URL?remark=glossary&urlname=http:%2F%2Fdownload-west.oracle.com%2Fdocs%2Fcd%2FB10501_01%2Fserver.920%2Fa96524%2Fglossary.htm%23432681

> Point 2 : The redo log records all changes made to data,
> including both uncommitted and committed changes.

http://www.oracle.com/pls/db92/db92.to_URL?remark=glossary&urlname=http:%2F%2Fdownload-west.oracle.com%2Fdocs%2Fcd%2FB10501_01%2Fserver.920%2Fa96524%2Fglossary.htm%23996859

>
> Q1.So any Transaction Rollback there are data duplication storage
> is happening.Means Rollback segment is storing the data as well
> as the rego log.Is it true?If true then why?

Figure out the difference between a transaction and recovery, and consider the issue of repeatable reads.

>
> Q2.But I have a doubt on my question also.Is rollback segment stores
> data or refresh it after stipulated hours or after every load???

Man, read the book again.
http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96524/b_deprec.htm#634941

jg

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