Re: Common mistakes when upgrading to 9i

netcomrade_at_karlson.dmitriev.net (NetComrade) wrote:
> Hi,
>
> We are finally on a path to upgrade from 8i (8.1.7.4) to 9i (9.2.0.1).
> I wanted to learn from your experiences on things that can go wrong.
> I am going to list a few things I've read up on, and if you're kind
> enough, you'll let me know if I missed anything important
>
> * sga_max_size should be examied
> * pga_aggregate_target default is 25MB, if set DB ignores
> sort_area_size
> hash_area_size
> bitmap_merge_area_size
>
> How do above two affect MTS (Shared Server)

Poorly, in my experience. Combining PGA_A_T with Shared Server seemed to make the CBO hopelessly confused. It got completely addicted to hash, at an expense of hundreds or thousands of fold slowdown. (Of course, we never should have been using Shared Server in the first place, but it only took me 18 months to win that battle.)

> * workarea_size_policy defaults to auto if pga_aggregate_target is set

Xho

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