Re: subselects doesn't work in v7.0.3

pgsql-bugs@postgresql.org wrote:
>
> jose (jose@sferacarta.com) reports a bug with a severity of 2
> The lower the number the more severe it is.
>
> Short Description
> subselects doesn't work in v7.0.3
>
> Long Description
> Version: PostgreSQL 7.0.3 on i686-pc-linux-gnu, compiled by gcc 2.95.2
>
> - I'm trying the following query in a table with 1973093 rows:
>
> EXPLAIN select count(*)
>    from marche
>    where ristampa = 'S'
>    and marca in
>    (
>    select marca from marche where ristampa is null and
>    data_lotto between '1998/07/01' and '1999/01/31'
>    );
>
> NOTICE:  QUERY PLAN:
> Aggregate  (cost=98854229180.08..98854229180.08 rows=1 width=4)
>   ->  Seq Scan on marche  (cost=0.00..98854229130.75 rows=19731 width=4)
>         SubPlan
>           ->  Materialize  (cost=50101.13..50101.13 rows=6577 width=12)
>                 ->  Seq Scan on marche  (cost=0.00..50101.13 rows=6577 width=12)
> EXPLAIN
>
> - but it takes to many time: (after about 16 hours I interrupt the query)

This is a known bug with IN ( ... ) and the use of indexes - you would
get better results using EXISTS.

Cheers,
                    Andrew.
--
_____________________________________________________________________
           Andrew McMillan, e-mail: Andrew@catalyst.net.nz
Catalyst IT Ltd, PO Box 10-225, Level 22, 105 The Terrace, Wellington
Me: +64 (21) 635 694, Fax: +64 (4) 499 5596, Office: +64 (4) 499 2267