What's in a Rollback Segment?

From: Jeremy Russell <jeremy.russell-NOTMYREALADDRESS_at_usa.net>
Date: Sat, 20 Jul 2002 06:24:13 GMT
Message-ID: <3d39010b.50393862@usenet.plus.net>

OK, maybe it's too early in the morning, and maybe I'm just dumb, but what - in detail - is written to a rollback segment in Oracle 8i? I understand that a rollback segment records undo info for a transaction (used Oracle long enough for that level of comprehension at least!), but it was my understanding that the entire block would be written out for potential read consistency, recovery, rollback purposes.

However, I have a feeling that may not be true.

If I issue

UPDATE emp SET ename='RUSSELL' where empno=7369;

does the entire block where this employee resides get written, is it the entire row or is it just the changed column?

If there's a link somewhere (technet or otherwise) that explains this, please let me have that, rather than taking up newsgroup bandwidth.

TIA Jeremy Russell Received on Sat Jul 20 2002 - 01:24:13 CDT