Re: Run Oracle without transactions?

Every time you commit LGWR has to write a complete number of O/S blocks to disc. On average every write of LGWR wastes half an operating system block.

If you commit every row, you may find that each write of LGWR is only a couple of blocks, which tends to be about 25% wastage (half a block out of every 2), but if you commit every couple of hundred rows you may find that LGWR writes about 50 blocks per write request, with wastage down to 1% (half a block in 50).

I used this to good effect recently in fact - one site I visited was generate 125Mb of redo writes in 10 seconds, of which 25Mb was wastage. When they changed to committing every 500 rows the total redo DROPPED to 113MB in 10 seconds, of which only 3Mb was wastage. Net result - they were processing 10% more data in the time (actual redo had gone up from 100Mb to 110 Mb - and this was a fair measure of work done).

--

Jonathan Lewis
Yet another Oracle-related web site: www.jlcomp.demon.co.uk

Doug Cowles wrote in message <37883818.5BC94C58_at_bigfoot.com>...
>Just curious, why is that going to drive up redo log wastage.
>One extra byte or two for every commit?
>Just wondering..
Received on Sun Jul 11 1999 - 04:28:01 CDT