Re: Planning counters in pg_stat_statements (using pgss_store)

On 2020/05/22 15:10, Andy Fan wrote:
>
>
> On Thu, May 21, 2020 at 3:49 PM Julien Rouhaud <rjuju123(at)gmail(dot)com <mailto:rjuju123(at)gmail(dot)com>> wrote:
>
> Le jeu. 21 mai 2020 à 09:17, Michael Paquier <michael(at)paquier(dot)xyz <mailto:michael(at)paquier(dot)xyz>> a écrit :
>
> On Thu, May 21, 2020 at 08:49:53AM +0200, Julien Rouhaud wrote:
> > On Tue, May 19, 2020 at 4:29 AM Andy Fan <zhihui(dot)fan1213(at)gmail(dot)com <mailto:zhihui(dot)fan1213(at)gmail(dot)com>> wrote:
> >> Thanks for the excellent extension. I want to add 5 more fields to satisfy the
> >> following requirements.
> >>
> >> int   subplan; /* No. of subplan in this query */
> >> int   subquery; /* No. of subquery */
> >> int   joincnt; /* How many relations are joined */
> >> bool hasagg; /* if we have agg function in this query */
> >> bool hasgroup; /* has group clause */
> >
> > Most of those fields can be computed using the raw sql satements.  Why
> > not adding functions like query_has_agg(querytext) to get the
> > information from pgss stored query text instead?
>
> Yeah I personally find concepts related only to the query string
> itself not something that needs to be tied to pg_stat_statements.
> ...
>
>
> Indeed cte will bring additional concerns about the fields semantics. That's another good reason to go with external functions so you can add extra parameters for that if needed.
>
>
> There are something more we can't get from query string easily. like:
> 1. view involved.   2. subquery are pulled up so there is not subquery
> indeed.  3. sublink are pull-up or become as an InitPlan rather than subPlan.
> 4. joins are removed by remove_useless_joins.

If we can store the plan for each statement, e.g., like pg_store_plans
extension [1] does, rather than such partial information, which would
be enough for your cases?

Regards,

[1]
http://pgstoreplans.osdn.jp/pg_store_plans.html
https://github.com/ossc-db/pg_store_plans

--
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION