Rollback I/O is done a block at a time, and block
images are rolled back for read-consistency - but I
think you may confuse people if you don't make the
I/O bit very clear. Rollback is recorded in records
where a record can be as small as 80 bytes, and
therefore in principle give you up to 400 rollback
records per rollback block. (I haven't tested that
figure - but it is a notional value for 32K blocks).
--
Jonathan Lewis
http://www.jlcomp.demon.co.uk
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Niall Litchfield wrote in message
<3d1b7aea$0$8510$cc9e4d1f_at_news.dial.pipex.com>...
>"Howard J. Rogers" <dba_at_hjrdba.com> wrote in message
>news:affpam$6m5$1_at_lust.ihug.co.nz...
>> > 2.. INSERT would need minimal (rowid + overhead per row) of Rollback.
>>
>> Incorrect. Incorrect in the sense that 'minimal' means different things
to
>> different people. An insert's rollback is pretty small compared with a
>> delete, that's for sure. But it's not nothing, and not even close to
being
>> practically nothing.
>
>And also the original poster seems to imagine that rollback io is done on a
>per row changed rather than a per block changed basis.
>
>
>--
>Niall Litchfield
>Oracle DBA
>Audit Commission UK
>
>
>
>
Received on Tue Jul 02 2002 - 15:09:43 CDT
