Re: Performance problem - help appreciated.

From: VC <boston103_at_hotmail.com>
Date: Tue, 30 Mar 2004 22:38:43 GMT
Message-ID: <TFmac.138311$1p.1795657@attbi_s54>

Pls. see below:

"Sybrand Bakker" <gooiditweg_at_sybrandb.demon.nl> wrote in message news:qqoj60hmmu5gdh8u69nkbj5dicob4ieink_at_4ax.com...
> On 30 Mar 2004 08:16:19 -0800, charlie3101_at_hotmail.com (Charlie
> Edwards) wrote:
>
> >So can anyone help?
> >Why does it suddenly ignore my first_rows hint?
> >Has anyone got any other suggestions on how I can solve my problem.
>
> Swap the order of the tables in the from clause, you have the driving
> table listed last and that should be first, using CBO

I am sorry to say that but the order of tables in the FROM clause is simply irrelevant since the CBO re-arranges them as it sees fit -- ther is no notion of the 'drivng' table under CBO. The order does matter under the RBO.

The tkprof output for all the scenarios would've been helpful, though.

> Make sure there are histograms on the indexed columns
> Make also sure optimizer_index_cost_adj and optimizer_index_caching
> are NOT at their defaults.
> Realize any outer join is just asking for awful execution plans.
>
>
> --
> Sybrand Bakker, Senior Oracle DBA
Received on Tue Mar 30 2004 - 16:38:43 CST