2011/4/23 Robert Haas <robertmhaas(at)gmail(dot)com>
> On Apr 18, 2011, at 1:13 PM, Uwe Bartels <uwe(dot)bartels(at)gmail(dot)com> wrote:
> > Hi Robert,
> > thanks for your answer.
> > the aggregate function I was talking about is the function I need to use
> for the non-group by columns like min() in my example.
> > There are of course several function to choose from, and I wanted to know
> which causes as less as possible resources.
> Oh, I see. min() is probably as good as anything. You could also create a
> custom aggregate that just always returns its first input. I've occasionally
> wished we had such a thing as a built-in.
I've once done "single" grouping function - it checks that all it's input
values are equal (non-null ones) and returns the value or raises an error if
there are two different values.
Best regards, Vitalii Tymchyshyn
In response to
pgsql-performance by date
|Next:||From: Josh Berkus||Date: 2011-04-25 18:06:47|
|Subject: Re: Issue with partition elimination|
|Previous:||From: Uwe Bartels||Date: 2011-04-24 19:01:36|
|Subject: Re: big distinct clause vs. group by|