-----Original Message----- From: Luís Roberto Weck [mailto:luisroberto@xxxxxxxxxxxxxxx] Sent: Thursday, September 19, 2019 2:30 PM To: Michael Lewis <mlewis@xxxxxxxxxxx> Cc: pgsql-performance@xxxxxxxxxxxxxxxxxxxx Subject: Re: Slow query on a one-tuple table WARNING: This email originated from outside of Perceptron! Please be mindful of PHISHING and MALWARE risks. Em 19/09/2019 14:21, Michael Lewis escreveu: > Is this result able to be repeated? Yes, I can consistently repeat it. Postgres version is 11.1. Other executions: Index Scan using assessoria_pkey on public.assessoria (cost=0.25..2.47 rows=1 width=62) (actual time=1.591..4.035 rows=1 loops=1) Output: asscod, asscambol Index Cond: (assessoria.asscod = 1) Buffers: shared hit=1187 Planning Time: 0.053 ms Execution Time: 4.055 ms Index Scan using assessoria_pkey on public.assessoria (cost=0.25..2.47 rows=1 width=62) (actual time=1.369..3.838 rows=1 loops=1) Output: asscod, asscambol Index Cond: (assessoria.asscod = 1) Buffers: shared hit=1187 Planning Time: 0.033 ms Execution Time: 3.851 ms ________________________________________________________________________________________________________________ But can you repeat it with "LIMIT 1"? Notice huge difference in "buffers hit" while doing (the same) Index Scan in two plans. Regards, Igor Neyman
