Re: Plan not skipping unnecessary inner join

On Sun, May 17, 2020 at 09:32:47AM -0300, Ranier Vilela wrote:
> I redid the same tests with vanila postgres and with empty tables.
> I'm surprised, why does the plan have 2550 rows in explain?

That's the *estimated* rowcount.

The planner tends to ignore table statistics which say the table is empty,
since that can lead to a terrible plan if it's not true (stats are out of date
or autovacuum threshold not hit).

See also here
https://www.postgresql.org/message-id/20171110204043.GS8563%40telsasoft.com

-- 
Justin