Re: simple LEFT JOIN giving wrong results ...

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От Marc G. Fournier
Тема Re: simple LEFT JOIN giving wrong results ...
Дата
Msg-id 20031211194236.H17041@ganymede.hub.org
обсуждение исходный текст
Ответ на Re: simple LEFT JOIN giving wrong results ...  (Tom Lane <tgl@sss.pgh.pa.us>)
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On Thu, 11 Dec 2003, Tom Lane wrote:

> "Marc G. Fournier" <scrappy@hub.org> writes:
> > So, I'm doing my LEFT JOIN wrong *somehow*, but its eluding me as to
> > what/how .. :(
>
> > ams=# select ct.ip_id, sum(ct.bytes) as traffic,
> >              avg(cs.bytes)::bigint as storage
> >         from company_00186.traffic ct
> >    left join company_00186.storage cs ON ( ct.ip_id = cs.ip_id AND
> >                                            month_trunc(cs.runtime) = '2003-12-01')
> >        where month_trunc(ct.runtime) = '2003-12-01' group by ct.ip_id;
>
> I suspect you do not want the month_trunc constraint to be included
> in the JOIN ON condition, only in WHERE.

'k, but then would that take in all storage for all dates, since I'm only
then joining on the ip_id?  right now, I only have storage #s for Dec, so
it wouldn't make any differences for this one, but ..

results are still way off though, even with removing it:
ip_id |   traffic    |   storage
-------+--------------+------------- 1088 |   1979325872 |  2119206061 1200 |  84004842024 |  3165073628 1227 |
45591571353|  4891683299 1179 |   3893192839 | 1194 |     77360968 |  1839676259 1134 |     17357504 |    24794553 1226
|  5836213601 | 1089 | 315424415080 | 10814211187
 
(8 rows)

By changing the query to:

ams=# select ip_id, sum(bytes),            (select avg(bytes)               from company_00186.storage cs
wheremonth_trunc(runtime) = '2003-12-01'                and cs.ip_id = ct.ip_id)::bigint as storage       from
company_00186.trafficct      where month_trunc(runtime) = '2003-12-01' group by ip_id;ip_id |     sum     |   storage
 
-------+-------------+------------- 1194 |     9670121 |  1839676259 1134 |     2169688 |    24794553 1226 |
5836213601| 1089 | 39428051885 | 10814211187 1088 |   247415734 |  2119206061 1200 | 10500605253 |  3165073628 1227 |
45591571353|  4891683299 1179 |  3893192839 |
 
(8 rows)

I can get the right results again, it jus doesn't seem as clean ;(
----
Marc G. Fournier           Hub.Org Networking Services (http://www.hub.org)
Email: scrappy@hub.org           Yahoo!: yscrappy              ICQ: 7615664


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