Re: Plan not skipping unnecessary inner join
I redid the same tests with vanila postgres and with empty tables. I'm surprised, why does the plan have 2550 rows in explain? regards, Ranier Vilela
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table statistics which say the table is empty, since that can lead to a terrible plan if it's not true (stats are out of date or autovacuum threshold not hit).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
Re: Plan not skipping unnecessary inner join
Em dom., 17 de mai. de 2020 às 10:31, Justin Pryzby escreveu: > 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). > Thanks for the explanation. regards, Ranier Vilela
