Re: How to tune a SQL with 4 sbu-queries?

dino

rewrite means to write again.

suppose you have a materialized view emp10 for employees in dept 10

eg

create materialized view emp10 as select * from emp where deptno = 10;

you could perhaps issue

select employee_name from emp where deptno = 10;

Oracle might decide with query rewite going on to instead issue

select employee_name from emp10; if it were faster. this is query rewrite oracle is satisfying you request by issuing an equivalent that it considers better.

HTH Niall
"Dino Hsu" <dino1.nospam_at_ms1.hinet.net> wrote in message news:qcv2rtgp9r7ui398et19spqklnq7o75n7f_at_4ax.com...
> Dear all,
>
> Thanks for replies from Sybrand, Galen, and Mark, I am doing something
> according to your advices, I will post the result.
>
> One more question is what on earth is 'query rewrite'? I encountered
> this when doing FBI (function-based index), and I met it again with
> MTV (materialized view). Jason Couchman mentioned it too. I cannot
> even figure out its literal meaning. What is 'rewrite'? Re-write what?
> Thanks for your help.
>
> Dino
>
Received on Wed Sep 26 2001 - 16:52:34 CDT