how about I'm a sql92 lover? :-)
the idea is to use index. but the engine only use index when it sees
"where". so, how about add "where w.tid = w.tid" to the first (or
both) select on the two sides of the except?
not tested. if work, please let us know, thanks.
Kai
On Thu, 2 Dec 1999, Adriaan Joubert wrote:
> Satyajeet Seth wrote:
> >
> > Hi
> > The query:
> > select * from webdata except select * from webdata1;
> > takes abysmally long .How can I optimise it?
> > The particulars are:
>
> You could try
>
> select * from webdata w
> where not exists
> (select * from webdata1 w1
> where w1.tid=w.tid
> ...
> )
>
> If you have the correct indexes on webdata1 this can be quite fast.
>
> Adriaan
>
> ************
>