On Tue, Mar 29, 2005 at 11:07:20 +0100, T E Schmitz <[EMAIL PROTECTED]> wrote:
Would the "SELECT DISTINCT origin" always cause a sequential table scan regardless whether there is an index on the origin column or not?
It's worse than that, SELECT DISTINCT cannot use a hash aggregate plan and will need to do a sort to eliminate duplicates. Unless the view is used in a way that restricts the candidate rows, this probably isn't going to be very fast. You might be better off changing the view to use GROUP BY instead of DISTINCT.
As far as I can see (via EXPLAIN), both DISTINCT and GROUP BY will lead to a sequentail scan. Is that correct?
If that's the case, I should come up with a different concept to obtain a list of ORIGINs.
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Regards/Gruß,
Tarlika Elisabeth Schmitz
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TIP 9: the planner will ignore your desire to choose an index scan if your
joining column's datatypes do not match
