I know companies that never use CBO, just because statistics slow down
performance if they aren't taken regularly. If only one table of a user has
statistics taken from it, it grately reduces speed of all other tables
queries under RBO. In general an oracle database can perform very well
without statistics and CBO. The example I talk about is a system with tables
less than 100000 rows some with queries joining tables on date basis. I saw
a query improve from seven seconds to less than 1 or 2 secs just by
partitioning the tables and the indexes, without statistics and CBO.
"Richard Foote" <richard.foote_at_bigpond.com> schreef in bericht
news:3wjv9.64478$g9.181412_at_newsfeeds.bigpond.com...
> Hi Daud,
>
> The RBO and myself have a number of things in common, the most obvious
being
> that we are fast approaching our used by date. However another thing we
are
> both rather hopeless at is pruning. I have killed more roses than I would
> like to admit and the RBO wouldn't know how to perform partition pruning
on
> a partitioned table if it's life depended on it (which I guess it does).
The
> RBO also wouldn't have the foggiest notion on using an effective
> partition-wise join.
>
> Therefore from a purely performance point of view, the RBO is kinda
> buggered.
>
> Cheers
>
> Richard
> "Daud" <daud11_at_hotmail.com> wrote in message
> news:f0bf3cc3.0210280202.1be923bf_at_posting.google.com...
> > Someone told me this:
> >
> > Partitioning has no effect on performance unless the Cost Based
> > Optimizer is used.
> >
> > Is that true? I find it a bit hard to believe but then I am not sure
> > since I dont know much about partitioning.
> >
> > rgds
> > Daud
>
>
Received on Tue Oct 29 2002 - 10:14:20 CST
