The following bug has been logged on the website:
Bug reference: 17110
Logged by: masterskipper
Email address: abhiroj95@gmail.com
PostgreSQL version: 11.10
Operating system: debian9
Description:
Hi,
Recently, we had to optimize a query that was behaving differently on
different databases (because data distribution and selectivity on each DB
were different). The problem is that it is very very difficult today to
understand why is the DB selecting the query plan it shows (and not other
plans). For e.g. why prefer sequential scan over index scan? what were the
costs that it calculated which made it prefer sequential scan?
Investigating such issues will become way more user friendly rather than
doing a guess work in and out. I believe this is a valid request and would
request you to please consider some time to fix it.
Many Thanks,
Abhiroj
