Re: Sum of multiplied deltas

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От Gerhard Wiesinger
Тема Re: Sum of multiplied deltas
Дата
Msg-id alpine.LFD.2.00.0906082008090.10072@bbs.intern
обсуждение исходный текст
Ответ на Re: Sum of multiplied deltas  (David Fetter <david@fetter.org>)
Ответы Re: Sum of multiplied deltas  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-general
Any hints for an 8.3 environment (currently)?

Thnx.

Ciao,
Gerhard

--
http://www.wiesinger.com/


On Mon, 8 Jun 2009, David Fetter wrote:

> On Mon, Jun 08, 2009 at 08:35:20AM +0200, Gerhard Wiesinger wrote:
>> Hello!
>>
>> I've the following data:
>> datetime | val1 | val2
>> time1    |    4 | 40%
>> time2    |    7 | 30%
>> time3    |   12 | 20%
>> ...
>>
>> I'd like to sum up the following:
>>
>> (7-4)*30% + (12-7)*20% + ...
>
> This is best done in 8.4 using Windowing.  Sadly, it's an 8.4-only
> feature, and dodgy hacks are the rule until you can use them.
>
> Cheers,
> David.
>>
>> datetime is ordered (and unique and has also an id).
>>
>> Rows are in the area of millions.
>>
>> How is it done best?
>> 1.) Self join with one row shift?
>> 2.) function?
>>
>> Any hint?
>>
>> Thnx.
>>
>> Ciao,
>> Gerhard
>>
>> --
>> http://www.wiesinger.com/
>>
>>
>> --
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>
> --
> David Fetter <david@fetter.org> http://fetter.org/
> Phone: +1 415 235 3778  AIM: dfetter666  Yahoo!: dfetter
> Skype: davidfetter      XMPP: david.fetter@gmail.com
>
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