Em qui., 19 de ago. de 2021 às 09:21, Masahiko Sawada <sawada.m...@gmail.com> escreveu:
> Hi all , > > It's reported on pgsql-bugs[1] that I/O timings in EXPLAIN don't show > the one for temp files. I think it's not a bug but could be an item > for PG15. As mentioned on that thread, this would be useful for users > in a case where temp buffers I/O used most of the time. So I've > written the patch for that. Please note that the patch includes only > to show temp buffer I/O timing to EXPLAIN but not other possibly > related changes such as pg_stat_statement improvements yet. > > Before (w/o patch): > postgres(1:14101)=# explain (analyze, buffers) select count(*) from > generate_series(1,100000); > QUERY PLAN > > ----------------------------------------------------------------------------------------------------------------------------------- > Aggregate (cost=1250.00..1250.01 rows=1 width=8) (actual > time=59.025..59.026 rows=1 loops=1) > Buffers: temp read=171 written=171 > -> Function Scan on generate_series (cost=0.00..1000.00 > rows=100000 width=0) (actual time=21.695..45.524 rows=100000 loops=1) > Buffers: temp read=171 written=171 > Planning Time: 0.041 ms > Execution Time: 70.867 ms > (6 rows) > > After (w/ patch): > postgres(1:28754)=# explain (analyze, buffers) select count(*) from > generate_series(1,100000); > QUERY PLAN > > ----------------------------------------------------------------------------------------------------------------------------------- > Aggregate (cost=1250.00..1250.01 rows=1 width=8) (actual > time=56.189..56.190 rows=1 loops=1) > Buffers: temp read=171 written=171 > I/O Timings: temp read=0.487 write=2.073 > -> Function Scan on generate_series (cost=0.00..1000.00 > rows=100000 width=0) (actual time=21.072..42.886 rows=100000 loops=1) > Buffers: temp read=171 written=171 > I/O Timings: temp read=0.487 write=2.073 > Planning Time: 0.041 ms > Execution Time: 59.928 ms > (8 rows) > > Feedback is very welcome. > The presentation seems a little confusing, wouldn't it be better? I/O Timings: shared/local read=xxxx write=xxx temp read=0.487 write=2.073 I think can remove this lines: + if (has_temp_timing) + appendStringInfoChar(es->str, ','); regards, Ranier Vilela
