On Sun, Aug 22, 2021 at 9:47 PM Masahiko Sawada <sawada.m...@gmail.com> wrote: > > On Thu, Aug 19, 2021 at 10:52 PM Ranier Vilela <ranier...@gmail.com> wrote: > > > > Em qui., 19 de ago. de 2021 às 09:21, Masahiko Sawada > > <sawada.m...@gmail.com> escreveu: > > > 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 > > Yeah, it looks better to add "shared/local".
Using the patch, I do feel like the EXPLAIN format of shared/local xxx, temp xxx is a bit confusing. If temp is going to be its own EXPLAIN IO timing category (as opposed to being summed with relation data block IO from local and shared buffers), then it seems like local and shared should be separated as well. shared xxx, local xxx, temp xxx With your patch applied, below is the top of the EXPLAIN output for a query joining a temporary table (so using local buffers) to a regular table (using shared buffers) and spilling the hash join (temp files). Aggregate (actual rows=1 loops=1) Buffers: shared read=4425, local read=4425 dirtied=4425 written=4423, temp read=5963 written=5963 I/O Timings: shared/local read=23.546, temp read=13.309 write=74.198 I found that using the same terminology as the "EXPLAIN BUFFERS" output but not using the same categories was kind of confusing. If it is only meaningful to distinguish between relation data IO and query temp file IO, then maybe the words used in I/O Timings in EXPLAIN should be "rel data" and "temp" or something like that. - Melanie
