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
