problem with slow select

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From: francescosaf <francescosaf(dot)152kao(at)mail(dot)webservertalk(dot)com>
To: pgsql-sql(at)postgresql(dot)org
Subject: problem with slow select
Date: 2004-04-21 15:00:23
Message-ID: francescosaf.152kao@mail.webservertalk.com
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Lists: pgsql-sql


hi

I have two tables:

table: XXXX
idcode varchar(15) -->references (idcode) table YYYY
latitude float
longitude float
time timestamp
p_a char(1)
barcode....
address....
idprog serial... -->primary key
flag boolean

table YYYY
idfact numeric(7,0) --->references .....
idcode varchar(15) --->primary key
name varchar(20)

I want to exctract the last operation of table XXXX for each idcode of
table YYYY where idfact=123

I HAVE THIS QUERY BUT IT IS TOO SLOW (10 SECONDS):

select XXXX.*,YYYY.name from YYYY,XXXX join (select
XXXX.idcode,max(XXXX.tempo) as tempo from XXXX,YYYY where
YYYY.idfact=123 and XXXX.idcode=YYYY.idcode group by XXXX.idcode)
temptable on (temptable.tempo=XXXX.tempo and
temptable.idcode=XXXX.idcode) where YYYY.idfact=123 and
XXXX.idcode=YYYY.idcode order by YYYY.name;

PLEASE HELP ME

--
francescosaf
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From: Rod Taylor <pg(at)rbt(dot)ca>
To: francescosaf <francescosaf(dot)152kao(at)mail(dot)webservertalk(dot)com>
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: problem with slow select
Date: 2004-04-26 18:58:00
Message-ID: 1083005880.30065.6.camel@jester
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On Wed, 2004-04-21 at 11:00, francescosaf wrote:
> hi
>
> I have two tables:

Please send results of EXPLAIN ANALYZE for the query in question.

Thanks