Redo Logs and Rollback Segments Relationships ?

From: Jonathan B. Joseph <josepj00_at_molbio.sbphrd.com>
Date: 1998/02/26
Message-ID: <34F57113.E8DD49D4@molbio.sbphrd.com>#1/1

I'm an Oracle newbie and I was recently reviewing a database creation script
and noticed that there were entries for creating both redo logs and rollback segments.
Since I thought that rollback segments were the physical components of the redo logs,
I need to understand how they are related. So I have the following questions:

Are rollback segments related to redo logs ?

When I execute an update, insert , or delete statement , does it get written to the redo log or rollback segment for the tablespace that I'm working in ? (ie., what happens to the redo log and/or rollback segment ?)

Do rollback segements compose the physical parts of a redo log ?

And what happens to the redo log and/or rollback segment, when I issue a commit ? Do do all the inserts, updates, deletes get removed from the rollback segment and redo log and the inserts, updates, deletes get written to the tablespace of the database that I'm working in?

When I do a rollback , does the rollback segment and/or redo log get erased (and the inserts, updates etc. not get applied to the database) ?

Thank you very much for any help,
Jonathan Joseph

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jon.joseph_at_jbjnet.com Received on Thu Feb 26 1998 - 00:00:00 CST