Bruno Wolff III wrote:
> On Thu, Aug 28, 2003 at 17:10:31 -0700,
> Ken Geis <kgeis(at)speakeasy(dot)org> wrote:
>
>>The query I want to run is
>>
>>select stock_id, min(price_date) from day_ends group by stock_id;
>
> The fast way to do this is:
>
> select distinct on (stock_id) stock_id, price_date
> order by stock_id, price_date;
Not according to the optimizer! Plus, this is not guaranteed to return
the correct results.
Unique (cost=3711244.30..3795942.42 rows=6366 width=8)
-> Sort (cost=3711244.30..3753593.36 rows=16939624 width=8)
Sort Key: stock_id, price_date
-> Seq Scan on day_ends (cost=0.00..361892.24 rows=16939624
width=8)