On Fri, May 22, 2020 at 3:51 PM Fujii Masao <masao.fu...@oss.nttdata.com> wrote: > > On 2020/05/22 15:10, Andy Fan wrote: > > > > > > On Thu, May 21, 2020 at 3:49 PM Julien Rouhaud <rjuju...@gmail.com > > <mailto:rjuju...@gmail.com>> wrote: > > > > Le jeu. 21 mai 2020 à 09:17, Michael Paquier <mich...@paquier.xyz > > <mailto:mich...@paquier.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.fan1...@gmail.com <mailto:zhihui.fan1...@gmail.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?
That'd definitely address way more use cases. Do you know if some benchmark were done to see how much overhead such an extension adds?
