Re: Expected accuracy of planner statistics

Arturo Perez <aperez(at)hayesinc(dot)com> writes:

> Can the DBA just set n_distinct? Sometimes s/he just knows what the
> value should be.

Having an expensive process run once in a while and setting this value also
sounds interesting. If it has to be calculated every time then this is a bad
thing, but having some kind of command or function to update it that could be
called when the database has a lower load would be interesting. For companies
that work from 8am to 5pm this could be scheduled to run every night...

> Then, of course, the questions becomes how to keep vacuum et al from
> messing it up.

It could not touch these setting if the specific command isn't called, it
could gain a new parameter "VACUUM FULL N_DISTINCT ..." to touch it (and then
we probably discard the extra command / function) or it could update these
settings when called with ANALYZE only...

--
Jorge Godoy <jgodoy(at)gmail(dot)com>