Re: SELECT LIMIT 1 VIEW Performance Issue

At 22:37 05/09/22, Merlin Moncure wrote:

> > >create or replace view VCurPlayer as select * from Player a
> > >where a.AtDate = (select Max(b.AtDate) from Player b where a.PlayerID=
> > >b.PlayerID);
>
>Here is a trick I use sometimes with views, etc.  This may or may not be
>effective to solve your problem but it's worth a shot.  Create one small
>SQL function taking date, etc. and returning the values and define it
>immutable.  Now in-query it is treated like a constant.

We don't use functions as a rule, but I would be glad to give it a try.
I would most appreciate if you could define a sample function and rewrite
the VCurPlayer view above. Both PlayerID and AtDate are varchar fields.

>Another useful application for this feature is when you have nested
>views (view 1 queries view 2) and you need to filter records based on
>fields from view 2 which are not returned in view 1.  Impossible?
>
>in view 2 add clause where v2.f between  f_min() and f_max(), them being
>immutable functions which can grab filter criteria based on inputs or
>values from a table.
>
>Merlin

Best regards,
KC.