Re: Is it useful to record whether plans are generic or custom?

On Thu, May 14, 2020 at 2:28 AM legrand legrand <legrand_legrand(at)hotmail(dot)com>
wrote:

> Hello,
>
> yes this can be usefull, under the condition of differentiating all the
> counters
> for a queryid using a generic plan and the one using a custom one.
>
> For me one way to do that is adding a generic_plan column to
> pg_stat_statements key, someting like:
> - userid,
> - dbid,
> - queryid,
> - generic_plan
>

Thanks for your kind advice!

> I don't know if generic/custom plan types are available during planning
> and/or
> execution hooks ...

Yeah, that's what I'm concerned about.

As far as I can see, there are no variables tracking executed
plan types so we may need to add variables in
CachedPlanSource or somewhere.

CachedPlanSource.num_custom_plans looked like what is needed,
but it is the number of PLANNING so it also increments when
the planner calculates both plans and decides to take generic
plan.

To track executed plan types, I think execution layer hooks
are appropriate.
These hooks, however, take QueryDesc as a param and it does
not include cached plan information.
Portal includes CachedPlanSource but there seem no hooks to
take Portal.

So I'm wondering it's necessary to add a hook to get Portal
or CachedPlanSource.
Are these too much change for getting plan types?

Regards,

--
Atsushi Torikoshi