Re: [HACKERS] generated columns

On Wed, 27 Dec 2017 at 17:31, Peter Eisentraut <
peter(dot)eisentraut(at)2ndquadrant(dot)com> wrote:

> On 9/12/17 15:35, Jaime Casanova wrote:
> > On 10 September 2017 at 00:08, Jaime Casanova
> > <jaime(dot)casanova(at)2ndquadrant(dot)com> wrote:
> >>
> >> During my own tests, though, i found some problems:
>
> Here is an updated patch that should address the problems you have found.
>
> > also is interesting that in triggers, both before and after, the
> > column has a null. that seems reasonable in a before trigger but not
> > in an after trigger
>
> Logically, you are correct. But it seems excessive to compute all
> virtual columns for every trigger. I don't know how to consolidate
> that, especially with the current trigger API that lets
> you look more or less directly into the tuple.
>

I wasn't sure where this thought about after triggers ended up.

Presumably stored values can just be read from storage, so no overhead in
after triggers?

Having the stored values show as NULL would be OK for virtual ones. But
what do we do if the column is NOT NULL? Do we still have nulls then?

It would be useful to have a way to generate the values, if desired. Not
sure how hard that is.

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