Re: Optimiser query

Mike Gahan wrote:
>
> Is there any way I can persuade the optimiser to use the indexes
> in case (2)? In my real application, T1 is very large.

Oracle allows the use of *hints*. For example, if Oracle decides to use one index and you *know* that it would be better to use a different one you could say:

  select /*+ index(tname, ndx_id ) */ last_name, first_name, id, dept   from tname ;

I'm sorry, but I haven't used hints all that much (like *never*) so I am not familiar enough with them to even be sure they will do what you want. I can't even refer you to any documentation about them. But you may want to play around with them and see what happens.

-- 
Tomm Carr
--
"Can you describe your assailant?"
"No problem, Officer.  That's exactly what I was doing when he hit me!"