On Fri, Jan 24, 2020 at 10:06 PM Julien Rouhaud <rjuju...@gmail.com> wrote: > > On Fri, Jan 24, 2020 at 6:55 AM Justin Pryzby <pry...@telsasoft.com> wrote: > > > > On Wed, Nov 13, 2019 at 11:39:04AM +0100, Julien Rouhaud wrote: > > > (moved to -hackers) > > > > > > On Tue, Nov 12, 2019 at 9:55 PM Andres Freund <and...@anarazel.de> wrote: > > > > > > > > This last point is more oriented towards other PG developers: I wonder > > > > if we ought to display buffer statistics for plan time, for EXPLAIN > > > > (BUFFERS). That'd surely make it easier to discern cases where we > > > > e.g. access the index and scan a lot of the index from cases where we > > > > hit some CPU time issue. We should easily be able to get that data, I > > > > think, we already maintain it, we'd just need to compute the diff > > > > between pgBufferUsage before / after planning. > > > > > > That would be quite interesting to have. I attach as a reference a > > > quick POC patch to implement it: > > > > +1 > > > > + result.shared_blks_hit = stop->shared_blks_hit - > > start->shared_blks_hit; > > + result.shared_blks_read = stop->shared_blks_read - > > start->shared_blks_read; > > + result.shared_blks_dirtied = stop->shared_blks_dirtied - > > + start->shared_blks_dirtied; > > [...] > > > > I think it would be more readable and maintainable using a macro: > > > > #define CALC_BUFF_DIFF(x) result.##x = stop->##x - start->##x > > CALC_BUFF_DIFF(shared_blks_hit); > > CALC_BUFF_DIFF(shared_blks_read); > > CALC_BUFF_DIFF(shared_blks_dirtied); > > ... > > #undefine CALC_BUFF_DIFF > > Good idea. Note that you can't use preprocessor concatenation to > generate something else than a token or a number, so the ## can just > be removed here.
Rebase due to conflict with 3ec20c7091e97.
show_planning_buffers-v3.diff
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