Re: idea - new aggregates median, listagg

From: Thom Brown <thombrown(at)gmail(dot)com>
To: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: idea - new aggregates median, listagg
Date: 2009-12-16 15:24:32
Message-ID: bddc86150912160724l3409ae6fua07b905d90ac7d35@mail.gmail.com
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2009/12/15 Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>

> Hello
>
> I am looking on new feature - ORDER clause in aggregate, and I thing,
> so we are able to effectively implement some non standard, but well
> known aggregates.
>
> a) function median - it is relative frequent request - with usually
> slow implementation
>
> b) function listagg (it is analogy of group_concat from MySQL) - it
> should simplify report generating and some other
>
> What is your opinion? Do you like to see these functions in core?
>
>
>
I'm probably missing the point here, but when I originally saw MySQL's
group_concat function, I found it odd that it featured ordering
functionality. Shouldn't the order by determined by the query itself?
Otherwise it's almost as if its separating the relationship between the
result column and the resultset.

Thom

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