Re: proposal: schema PL session variables

On 2/10/16 1:17 PM, Pavel Stehule wrote:
>
>
> 2016-02-10 20:10 GMT+01:00 Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com
> <mailto:Jim(dot)Nasby(at)bluetreble(dot)com>>:
>
> On 2/10/16 1:04 PM, Pavel Stehule wrote:
>
>
> BTW, if all that's desired here are session variables for
> plpgsql, I
> think it makes a lot more sense to start with implementing
> per-function session variables. That's a lot simpler
> design-wise and
> is something we should have anyway. You don't necessarily want

> It is too simple and too like workaround :) I can do it this in plpgsql
> extension probably.

I think it's something people will definitely want. If we don't have it,
then they're going to be using schema variables as a work-around because
they can't do a private static variable inside a single function.

> Most importantly, since this effects only plpgsql and only
> individual functions, the design is simple and should be easy to
> commit in 9.6. I don't have the same confidence with schema variables.
>
>
> My target is not 9.6 - next commitfest will be full - finishing multi
> CPU queries, logical replication, .. and I have still three opened
> patches. But if we find a agreement in this spring, I can implement it
> in summer, and it can be in upstream in early 9.7 commitfest. I know,
> this topic is difficult, so have to start it now.

Sure. I think it would be useful to have a wiki page with info as it
gets ironed out. A good starting point would be use cases. One that I
don't think has been considered is different extensions adding/using
different schema variables. Questions like should extension A have
direct access to variables for extension B.
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com