Em qui., 19 de ago. de 2021 às 09:21, Masahiko Sawada <sawada.mshk@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?
