Notes inline
--
Regards
Jonathan Lewis
http://www.jlcomp.demon.co.uk
The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html
March 2004 Hotsos Symposium - The Burden of Proof
Dynamic Sampling - an investigation
March 2004 Charlotte OUG (www.cltoug.org) CBO Tutorial
April 2004 Iceland
June 2004 UK - Optimising Oracle Seminar
"srivenu" <srivenu_at_hotmail.com> wrote in message
news:1a68177.0403022222.47899f13_at_posting.google.com...
> Whereas for an update, each block is pinned in current mode once for
> every row updated. so if you have to update 10 rows in a block, the
> block in pinned in current mode 10 times. There must be some reason
> why all the rows in a block are not updated at one go while the block
> is pinned in current mode.
On an update, Oracle
Generates a redo record for the log buffer
acquires space in the log buffer
pins the undo block and the data block
writes the record into the log buffer
updates the undo block
updates the data block
releases the pins
Then repeats the process for each index
affected by the row update.
It would not be a trivial exercise for Oracle Corp.
to modify the code to handle multiple updates to
a single block as a single event. However, it does
appear to have been done in (at least some cases in)
10g.
Received on Wed Mar 03 2004 - 02:14:22 CST
