Re: EXPLAIN PLAN madness!

In a sudden spasm of awareness,
Ed Stevens doodled thusly:

>
>On both databases we find:
> hash_area_size = 0
> hash_join_enabled = true
> hash_multiblock_io_count = 1
>these are defaulted values, there is no mention of them in the
>init.ora files. How about differences in some memory spec in the SGA?
>

block sizes different?

Also, db_multiblock_read-size (or whatever its spelling is nowadays) makes a huge diff. So does sort_area-size and its relationship to other parameters such as temp tablespace extents and such. I've found all of those make a difference in the darn thing selecting hash joins or not.

Because of these "undocumented" consistencies, I've now taken to disable the hash joins unless I absolutely have to have them. Too dangerous otherwise.

Cheers
Nuno Souto
nsouto_at_optushome.com.au.nospam Received on Fri Nov 16 2001 - 03:49:54 CST