Re: 9i multi cache buffer

in article jmbB9.77282$g9.218121_at_newsfeeds.bigpond.com, Howard J. Rogers at howardjr2000_at_yahoo.com.au wrote on 11/15/02 10:59 AM:

> My troubles start when Oracle introduces a new feature (such as multiple
> blocksizes or ASSM) which then get touted as the latest cure-all and hence
> get implemented without due consideration.

We never, ever, ever intended multiple blocksizes to be used primarily as a performance enhancement - it was done to make transportable tablespaces easy to use between an OLTP and DW system, where the 'in use' blocksizes may vary. And then, the aim is that you would use it only to stage the moved data, and then merge or CTAS into the actual warehouse data.

As a side note, during the original inhouse discussion of the feature,it was mentioned that multiple blocksizes did also have some performance tuning advantages - unfortunately, this then became over emphazised in the training and the doc, and has fast become another Oracle myth. This situation has now been reversed, and newer updates to the doc and training deliberately under emphasize the performance value of this feature.

The reality is that for most workloads (and I'd dare to say all customer workloads), the performance benefits from multiple block sizes will not make a significant impact, and in fact, I doubt would be measurable at all.

Hopefully this will close this thread (as it did the one that went through Oracle about 6 months ago on this same topic) Received on Fri Nov 15 2002 - 19:58:13 CST