Michael Lewis <mlewis@xxxxxxxxxxx> writes: > Simplified example query- > explain > select * from organizations o where id = id; > On a PG10 instance I get- > Seq Scan on organizations o (cost=0.00..4.21 ***rows=1*** width=37) > Filter: (id = id) > On a PG11 instance with the same or very very similar data, I get- > Seq Scan on organizations o (cost=0.00..5.70 ***rows=270*** width=37) > Filter: (id IS NOT NULL) > Given this is a not null field, it translates to "is true" basically. The > real query that this example was extracted from apparently had a typo in > the join resulting in this bogus id = id condition, but I still curious > about where this estimate change comes from. It's an intentional v11 change, cf https://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=8ec5429e2 regards, tom lane
