Sybrand Bakker <postbus_at_sybrandb.demon-verwijderdit.nl> wrote in message news:<1r6qmu0p4j1qkn41gaknikiu7g19vqahsv_at_4ax.com>...
>
> Bind variables: this means CBO ignores histograms (but you might not
> have them at all you don't specify), and assumes an even distribution
> of the data.
> RBO, of course, doesn't assume anything about distribution (so it
> *definitely doesn't have a much brighter outlook), it just uses an
> index wherever it can.
> You could try playing around with optimizer_index_cost_adj and similar
> parameters, apparently full table scans are considered 'cheap'
> Generically, I would however start with the FIRST_ROWS and the
> ORDERED, and of course there is event 10053 which will dump the
> rationale of CBO in a trace file. The Jonathan Lewis book has a
> description of the output.
>
> Hth
>
>
> Sybrand Bakker, Senior Oracle DBA
>
> To reply remove -verwijderdit from my e-mail address
Thanks for your help Sybrand
Received on Thu Aug 29 2002 - 09:34:42 CDT
