Re: Keeping top N records of a group - Mailing list pgsql-general

From Andreas Kretschmer
Subject Re: Keeping top N records of a group
Date
Msg-id 20160514123434.GA28259@tux
Whole thread Raw
In response to Keeping top N records of a group  (Alex Magnum <magnum11200@gmail.com>)
List pgsql-general
Alex Magnum <magnum11200@gmail.com> wrote:

> Hi,
> i want to archive data and am looking for a query to replace a rather slow
> function i am currently using.
>
> The idea is that for every sym and doc_key I want to keep the records of the
> top 2 sources. Eg. in below table I want to archive 

sounds like a case for window-functions here (maybe row_number() or
rank()), please read that for the start:

http://stackoverflow.com/questions/7613785/postgresql-top-n-entries-per-item-in-same-table



Regards, Andreas Kretschmer
--
Andreas Kretschmer
http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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