Group by and limit

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От Reid Thompson
Тема Group by and limit
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Msg-id 4CD0B077.2080700@ateb.com
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Ответы Re: Group by and limit  (Dimitri Fontaine <dimitri@2ndQuadrant.fr>)
Список pgsql-general
Reposting as I noticed that the original was in reply to a different subject.


Hey Folks – have a coded myself into a corner yet?

I have a situation with a select count / group by / order by query that I need to limit each group to 500
entries. Not seeing a way to do this in a single query, do I need to use multiple queries?
Group x has about 200 entries in it; group y has about 5-8k per x.

select x, y, count(*) as counter from mytable
group by x, y
order by x, counter, y


I only want the first 500 for each x.

Any tips or tricks someone might know would be appreciated.

I’m using postgres 8.3.7.



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