Re: Interpolation problem - pg 12.4 - full correct version!

On Wed, Aug 19, 2020 at 11:51 AM Pól Ua Laoínecháin <linehanp(at)tcd(dot)ie> wrote:

>
> I think my *MAJOR* problem is that I've developed what is,
> essentially, a totally brute force approach - and this simply won't
> work at the scenario becomes more complex - take a look at the CASE
> statement - it's horrible and would only become exponentially worse as
> the number NULLs rises.
>
> So, my question is: Is there a recognised technique (using SQL only,
> not PL/pgSQL - soutions based on the latter are easy to find) whereby
> I can do a basic Linear Interpolation?
>
>
I don't have a recognized technique, nor care to ponder one right now, but
what you've described would best be done in pure SQL using WITH RECURSIVE,
which provides an iterative approach to SQL result building. Which is more
commonly done in a procedural language. The algorithm you describe is an
iterative algorithm and so I'm wondering why place the arbitrary
restriction on using pure SQL when it likely wouldn't provide a very
readable nor performant solution relative to a procedural (pl/pgsql or
otherwise) one?

David J.