Re: Change db_block_size

Nuno Souto wrote:
>
> In a valiant and sublime effort,Howard J. Rogers
> dipped a thumbnail in soot and doodled:
>
> >But that's what the Recycle Pool is for, in the first place. Tucking BLOB
> >data out of the way so that it doesn't interfere with the rest of your cache
>
> Yeah, the problem is that there is only one recycle pool. If I have
> various types of application running in a single instance, I want
> finer control than just a single "bit bucket". It's only too easy to
> overwhelm the current three, jointly or "severally" (how's that for
> borrowing a banking term?). :-)
>
> >
> >Put it another way: whatever is the block size that makes for optimal
> >retrieval of LOB data will also be the block size that makes for optimal
> >retrieval of any other form of data.
>
> Hmmm, disagree. In general, BLOB stuff will be retrieved/processed
> one by one. Which is completely different from the requirements of,
> say, a data mart. Where full scans combined with short indexed
> retrieves may be required. Each requires a different strategy for
> best block size. Even with today's boxes. Not saying that tomorrow
> that won't change, mind you!
>
> >
> >I can see years ahead of me, having to deal with people who think variable
> >block size is the answer to all their woes!! Grrrrr. Just think
> >'transportable tablespaces', and the feature makes sense. Outside of
> >that....
> >
>
> Yeah, unfortunately people will always look for "silver bullets" that
> will "solve" all problems. Been like that for ages. Still well
> remember the fragmentation one. We are gonna see databases with block
> sizes galore for sure.
> <groan>
>
> Cheers
> Nuno Souto
> nsouto_at_optushome.com.au.nospam

Given the new mid point insert/touch count alogrithm, you've got something akin (and I know this is stretching it) to a keep and recycle concept on each buffer chain - I've seen sites where KEEP and RECYCLE made profound improvements to 8.0, but when upgraded to 8i, the buffer performance on those sites ran a treat without using a keep/recycle at all.

Cheers

-- 
==============================
Connor McDonald

http://www.oracledba.co.uk

"Some days you're the pigeon, some days you're the statue..."