On Jun 14, 2:18 pm, zigzag...@yahoo.com wrote:
> On Jun 14, 2:30 pm, "fitzjarr...@cox.net" <fitzjarr...@cox.net> wrote:
>
>
>
>
>
> > On Jun 14, 1:10 pm, zigzag...@yahoo.com wrote:
>
> > > I am not using function based indexes or materialized views. If I set
> > > this parameter=FALSE, will cost optimzer do something?. What are the
> > > advantages of setting this parameter Query_rewtite_enabled=TRUE.
>
> > Give us the release of Oracle you're using and we can tell you. I can
> > tell you that from 8.1.6 onwards query_rewrite_enabled is no longer
> > necessary when using function-based indexes. From 8.1.6 through
> > 9.2.0.8 setting that parameter to TRUE changes the rules for
> > transitive closure (this is fixed in 10g) causing the estimated
> > cardinality for affected queries, and thus the execution plans, to be
> > incorrect.
>
> > Post the release of Oracle you're using, to four numbers (8i, 9i, 10g
> > are not proper responses). You'll get an accurate answer after you do
> > so.
>
> > David Fitzjarrell
>
> Sorry, I am using Oracle 9.2.0.6 on Windows 2003.- Hide quoted text -
>
> - Show quoted text -

Then the transitive closure issue affects you should you decide to set
query_rewrite_enabled to TRUE. Jonathan Lewis wrote about this in
"Cost-Based Oracle Fundamentals", pp. 141-144.


David Fitzjarrell