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List:       postgresql-general
Subject:    Re: Aggregate functions on groups
From:       Rich Shepard <rshepard () appl-ecosys ! com>
Date:       2019-08-31 14:29:39
Message-ID: alpine.LNX.2.20.1908310724190.16819 () salmo ! appl-ecosys ! com
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On Sat, 31 Aug 2019, Morris de Oryx wrote:

> Your tributaries and fish master tables make sense. If I read your code
> right, you're grouping by too many columns. I flattened the data into a
> survey table for this simple example:

Morris,

I'm still learning about postgres groups. My approach is to group on the
column of interest, then add more when psql tells me to do so.

> select tributary,
>       common_name,
>       scientific_name,
>       sum(count_value) as fish_seen,
>       count(count_value) as observations_made
>
>   from survey
>
>   group by 1,2,3 -- The GROUP BY clause can use positions on the select
> list, if you feel like typing less.

I will look more at this approach; at first glance it appears to address one
query but not all those needed.

> But this is not why I'm answering. I'm responding as I wanted to make sure
> that you're aware of the pg-similarity extension:
> https://salsa.debian.org/postgresql/pg-similarity

Thanks for the URL. I'll definintely read about similarity.

Regards,

Rich


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