does max_connections affect the query planner

Bob Jolliffe <[email protected]> Tue, 17 Sep 2019 08:40:53 +0000

Newsgroups	gmane.comp.db.postgresql.performance
Message-ID	<CACd=f9fE5k6FNc=zovUY0ohEJcYhqasdW+=bm2_6Y-H9UDTvGQ@mail.gmail.com>

Hi

We are trying to diagnose why postgres might be making poor decisions
regarding query plans.  One theory is that it does not assume it has
the memory suggested in effective_cache_size.

We do know that max_connections is set quite high (600) when we don't
really expect more than 100.  I wonder does the planner take
max_connections x work_mem into account when considering the memory it
has potentially available?

Regards
Bob