Re: how do you write aggregate function
От | Justin |
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Тема | Re: how do you write aggregate function |
Дата | |
Msg-id | 47D54D5B.5030301@emproshunts.com обсуждение исходный текст |
Ответ на | Re: how do you write aggregate function (Martijn van Oosterhout <kleptog@svana.org>) |
Ответы |
Re: how do you write aggregate function
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Список | pgsql-general |
i wish that could work but need to keep track of the individual weights as its a percentage of the total amount of the weight.
I would never have thought the performance of the Array would suck this bad.
Martijn van Oosterhout wrote:
I would never have thought the performance of the Array would suck this bad.
Martijn van Oosterhout wrote:
On Sun, Mar 09, 2008 at 11:40:47AM -0500, Justin wrote:I got the aggregate function for weighted average done. I finely left alone for more than 10 minutes to actual get it written. It takes 2 value input Weight and the Value. it will sum the weighted entries to create the constant then does the normal formula, but does not percentage number but averaged number. A simple change on the return line it can do percentages.If you're looking for performance, ISTM the best option would be to simply accumulate the weights and value*weight as you go and do a division at the end. That seems likely to beat any implementation involving array_append. Have a nice day,
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