Re: ** can two processes use the same rollback extent

Yes Jonathan:

I think that 400 byte concept came from one of the TPC benchmarks during Oracle 7 (or ORacle 6) days where the average undo size for a transcation was around 380+ bytes. So they had rounded that to 400 bytes and a maximum of 5 blocks will be linked to the freelist in the undo segment header.

THis is called 'free extent pool' and the structure and the blocks are clearly visible in the undo header dumps.

Regards,
K Gopalakrishnan
Bangalore, INDIA

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Wednesday, December 03, 2003 1:59 PM

>
> A single block can only be 'owned' by one transaction
> at a time, but when a transaction commits, it may put
> its last undo block into that segment's 'free pool' list if there
> is a lot of free space left in the block so that it can be made
> available for new transactions . (Gaja Vaidyanatha quoted
> 400 bytes as the limit).
>
>
> Regards
>
> Jonathan Lewis
> http://www.jlcomp.demon.co.uk
>
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> ----- Original Message -----
> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> Sent: Wednesday, December 03, 2003 3:59 AM
>
>
> i can answer the first part of your question..
> YES, two transactions can write on the same extent of an RBS, i think the
> restriction is at the block level,
> this was true until 8i, might have changed in 9 +
>
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Jonathan Lewis
> INET: jonathan_at_jlcomp.demon.co.uk
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: K Gopalakrishnan
  INET: kaygopal_at_yahoo.com

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