Hi, On 2020-10-16 10:42:43 +0300, e.sokol...@postgrespro.ru wrote: > For some distributions of data in tables, different loops in nested loop > joins can take different time and process different amounts of entries. It > makes average statistics returned by explain analyze not very useful for > DBA. > To fix it, here is the patch that add printing of min and max statistics for > time and rows across all loops in Nested Loop to EXPLAIN ANALYSE. > Please don't hesitate to share any thoughts on this topic!
Interesting idea! I'm a bit worried that further increasing the size of struct Instrumentation will increase the overhead of EXPLAIN ANALYZE further - in some workloads we spend a fair bit of time in code handling that. It would be good to try to find a few bad cases, and see what the overhead is. Unfortunately your patch is pretty hard to look at - you seem to have included your incremental hacking efforts? > From 7871ac1afe7837a6dc0676a6c9819cc68a5c0f07 Mon Sep 17 00:00:00 2001 > From: "e.sokolova" <e.sokol...@postgrespro.ru> > Date: Fri, 4 Sep 2020 18:00:47 +0300 > Subject: Add min and max statistics without case of > parallel workers. Tags: commitfest_hotfix. > From ebdfe117e4074d268e3e7c480b98d375d1d6f62b Mon Sep 17 00:00:00 2001 > From: "e.sokolova" <e.sokol...@postgrespro.ru> > Date: Fri, 11 Sep 2020 23:04:34 +0300 > Subject: Add case of parallel workers. Tags: > commitfest_hotfix. > From ecbf04d519e17b8968103364e89169ab965b41d7 Mon Sep 17 00:00:00 2001 > From: "e.sokolova" <e.sokol...@postgrespro.ru> > Date: Fri, 18 Sep 2020 13:35:19 +0300 > Subject: Fix bugs. Tags: commitfest_hotfix. > From 7566a98bbc33a24052e1334b0afe2cf341c0818f Mon Sep 17 00:00:00 2001 > From: "e.sokolova" <e.sokol...@postgrespro.ru> > Date: Fri, 25 Sep 2020 20:09:22 +0300 > Subject: Fix tests. Tags: commitfest_hotfix. Greetings, Andres Freund
