Re: Select values by interval

On Mon, Nov 23, 2015 at 10:22 AM, Andreas Kretschmer <
akretschmer(at)spamfence(dot)net> wrote:

> Markus Wolters <MarkusWolters(at)gmx(dot)de> wrote:
>
> > Hi all,
> >
> > I have a table with value and timestamp columns. What I like to do (but
> am unable to find a solution) is to select the last(value) timestamp
> combination in every X minute interval where timestamp is between N and M.
> Is this possible with pgsql?
> >
>
> maybe somethink like
>
> select *, row_number() over (partition by to_char(timestamp, 'yyyy-mm-dd
> hh24:mm') order by ... desc) ...
>
>
> and then pick all with row_number = 1
>
> *untested*
>

​Unproven but whenever you have a query of this form (row_number = 1) you
should consider/test whether using DISTINCT ON with an appropriate ORDER BY
clause gives you the answer faster and/or more clearly.

David J.​