Re: Finding date intersections

On Fri, Oct 24, 2014 at 11:02 AM, David G Johnston <
david(dot)g(dot)johnston(at)gmail(dot)com> wrote:

> John McKown wrote
> >> insert into sales values
> >> (tstzrange('2014-1-1', '2014-1-2')),
> >> (tstzrange('2014-1-2', '2014-1-3')),
> >> (tstzrange('2014-1-2', '2014-1-4')),
> >> (tstzrange('2014-1-5', '2014-1-6'));
> >>
> >> -- want back:
> >> -- tstzrange('2014-1-1', '2014-1-4')
> >> -- tstzrange('2014-1-6', '2014-1-6')
> >>
>
> I presume the second output row should be [5,6)...
>

Yes, sorry. And I suppose the third argument to each of those should be
'[)'.

>
> And why are you using a timestamp range when your data are dates?
>

Didn't want to type our the hours, my my real situation involves
timestamptz's.

>
> My first thought is to explode the ranges into distinct dates, order them
> inside a window, use lag(...) to find breaks,p and assign groups, the for
> each group take the min and max of the group and form a new range. Not
> sure
> exactly what the SQL looks like - especially the range explosion - but
> should technically work even though performance may suck. Probably want to
> use lateral and generate_series(...) if you are on a more recent version.
>

Thanks! I'll look into this.

>
> David J.
>
>
>
>
>
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