so 17. 10. 2020 v 0:11 odesílatel Anastasia Lubennikova < a.lubennik...@postgrespro.ru> napsal:
> On 16.10.2020 12:07, Julien Rouhaud wrote: > > Le ven. 16 oct. 2020 à 16:12, Pavel Stehule <pavel.steh...@gmail.com> a > écrit : > >> >> >> pá 16. 10. 2020 v 9:43 odesílatel <e.sokol...@postgrespro.ru> napsal: >> >>> Hi, hackers. >>> For some distributions of data in tables, different loops in nested loop >>> joins can take different time and process different amounts of entries. >>> It makes average statistics returned by explain analyze not very useful >>> for DBA. >>> To fix it, here is the patch that add printing of min and max statistics >>> for time and rows across all loops in Nested Loop to EXPLAIN ANALYSE. >>> Please don't hesitate to share any thoughts on this topic! >>> >> >> +1 >> >> This is great feature - sometimes it can be pretty messy current limited >> format >> > > +1, this can be very handy! > >> Cool. > I have added your patch to the commitfest, so it won't get lost. > https://commitfest.postgresql.org/30/2765/ > > I will review the code next week. Unfortunately, I cannot give any > feedback about usability of this feature. > > User visible change is: > > - -> Nested Loop (actual rows=N loops=N) > + -> Nested Loop (actual min_rows=0 rows=0 max_rows=0 > loops=2) > This interface is ok - there is not too much space for creativity. I can imagine displaying variance or average - but I am afraid about very bad performance impacts. Regards Pavel > > Pavel, Julien, could you please say if it looks good? > > -- > Anastasia Lubennikova > Postgres Professional: http://www.postgrespro.com > The Russian Postgres Company > >
