From: | Ellen Cyran <ellen(at)urban(dot)csuohio(dot)edu> |
---|---|
To: | Stephan Szabo <sszabo(at)megazone23(dot)bigpanda(dot)com> |
Cc: | <pgsql-sql(at)postgresql(dot)org> |
Subject: | Re: slow group by query |
Date: | 2002-11-19 16:26:15 |
Message-ID: | 5.1.1.6.0.20021119112128.01ab52e0@wolf.csuohio.edu |
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Thread: | |
Lists: | pgsql-sql |
I had to modify your query somewhat, but the one below that is pretty much
the same took
about 12 seconds so once I run it on five years it will take just as
long. Thanks for the
suggestion though.
select distinct on (b.msa_code, b.sic, b.own, b.ind_div)
b.msa_code, b.sic, b.own, b.ind_div, y1975.emp from
tbl_bls_msa as b left outer join (select msa_code, sic, own, ind_div, emp
from tbl_bls_msa as bls
where bls.year='1975' ) as y1975
on (b.msa_code=y1975.msa_code and
b.sic=y1975.sic and b.own=y1975.own and b.ind_div=y1975.ind_div)
where b.msa_code in ('1680', '1640', '0040', '0120', '0080');
I would be interested in knowing more about what postgres extensions are
available. Where
are those documented at?
>Have you tried doing the subqueries in from? Right now you're running
>each subquery once for each output row AFAICS.
>
>Maybe something like (doing only one year for example - and using a
>postgres extension), would work...
>
>select distinct on (b.msa_code, b.sic, b.own, b.ind_div)
> b.msa_code, b.sic, b.own, b.ind_div, y1975.emp1975 from
>tbl_bls_msa as b left outer join (select emp from tbl_bls_mas as bls
> where bls.year='1975') y1975 on (b.msa_code=y1975.msa_code and
> b.sic=y1975.sic and b.own=y1975.own and b.ind_div=y1975.ind_div)
>where msa_code in ('1680', '1640', '0040', '0120', '0080');
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