Re: Optimizer picks an ineffient plan

Well, it's unfortunate that you feel that way, because SQL Server handles it
correctly.


"Tom Lane" <tgl@sss.pgh.pa.us> wrote in message
news:4375.1062643465@sss.pgh.pa.us...
> Greg Stark <gsstark@mit.edu> writes:
> > "Bupp Phillips" <hello@noname.com> writes:
> >> select * from customer order by customer_id, first_name;
> >> [ where customer_id is the primary key ]
>
> > However you do have a point. In this case I don't think postgres even
> > considers using the index.
>
> It will not, since the index does not appear to provide the correct sort
> order.
>
> > However I'm not sure I see a lot of cases where this would come up.
>
> Yes, that's the real crux of the matter.  Should the optimizer spend
> cycles on *every* query to detect cases where the user has written
> useless sort keys?  I've got grave doubts that it's a win.  ISTM such
> an optimization penalizes the folk who write their queries well to
> benefit those who are careless.
>
> regards, tom lane
>
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