Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> c.d.o.server -> Re: What's in a Rollback Segment?

Re: What's in a Rollback Segment?

From: Jeremy Russell <jeremy.russell-NOTMYREALADDRESS_at_usa.net>
Date: Sat, 20 Jul 2002 08:25:57 GMT
Message-ID: <3d391d91.57696583@usenet.plus.net>


Aha, figured you'd be the first responder - love that timezone difference.

So, to paraphrase for my own understanding:

A follow-up - if that transaction then updates another row, does it write rollback info to the currently used block (until that block is full) or does each DML statement in the same transaction acquire a further block?

Jeremy

On Sat, 20 Jul 2002 17:38:17 +1000, "Howard J. Rogers" <howardjr2000_at_yahoo.com.au> wrote:

>It's just the column of the row being updated. Your few-byte transaction is
>thus going to occupy an entire 8192 bytes of a rollback segment (ie, a
>transaction always occupies an entire rollback block, however small it is in
>itself).
>
>Regards
>HJR
>
>
>"Jeremy Russell" <jeremy.russell-NOTMYREALADDRESS_at_usa.net> wrote in message
>news:3d39010b.50393862_at_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 - 03:25:57 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US