Re: SELECT DISTINCT Performance Issue

On 6/2/05, K C Lau <KCLau@attglobal.net> wrote:
...
>
> select DISTINCT ON (PlayerID) PlayerID,AtDate from Player  where
> PlayerID='22220' order by PlayerID desc, AtDate desc;
> The Player table has primary key (PlayerID, AtDate) representing data over
> time and the query gets the latest data for a player.
>
>
...
> esdt=> explain analyze select DISTINCT ON (PlayerID) PlayerID,AtDate from
> Player
>   where PlayerID='22220' order by PlayerID desc, AtDate desc;
>   Unique  (cost=0.00..2507.66 rows=1 width=23) (actual time=0.000..187.000
> rows=1 loops=1)
>     ->  Index Scan Backward using pk_player on player  (cost=0.00..2505.55
> rows=8
> 43 width=23) (actual time=0.000..187.000 rows=1227 loops=1)
>           Index Cond: ((playerid)::text = '22220'::text)
>   Total runtime: 187.000 ms
>

Is PlayerID an integer datatype or a text datatype.  It seems like
PlayerID should be an integer data type, but postgres treats PlayerID
as a text data type.  This is because the value '22220' is quoted in
your query.  Also, the explain analyze output shows "Index Cond:
((playerid)::text = '22220'::text".

George Essig