Re: proposal: simple query profile and tracing API

út 13. 11. 2018 v 13:12 odesílatel legrand legrand <
legrand_legrand(at)hotmail(dot)com> napsal:

> Hello Pavel,
>
> What about using wait events and a trigger on pg_stat_activity ?
>

pg_stat_activity should not to show fresh data. Using pg_stat_activity can
be too expensive for fast queries

> just :
>
> * create a functions to get current query signature (queryid) for a pid
>
> (not the top_level_query given for pl/pgsql blocks or triggers but the
> active one)
>
> * add some kind of active events to track planning (in an extension with a
> planning hook)
>
> and populate some continuous views as proposed by pipelinedb (a very
> flexible solution).
>
> Yes, I know a trigger is not possible, and overhead of continuous views has
> not been verified,
> then some high frequency sampling on pg_stat_activity could help (I can
> provide examples for f_get_current_queryid(pid), active event for planning
> hook, continuous views)
>
> An other solution: a customized version of pgsentinel (for high frequency
> sampling):
>

I don't believe to sampling method - I talk about less than 10ms queries, I
would to see a 2-3ms planning time, 2-5ms waitings - and it means sampling
aboy 2ms, what is expensive

Regards

Pavel

>
> see
>
> https://www.postgresql-archive.org/Proposal-Add-accumulated-statistics-for-wait-event-td6030800.html#a6031384
>
> Regards
> PAscal
>
>
>
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