Re: BRIN index which is much faster never chosen by planner

The planner might be able to get a better estimate on the number of
matching rows if the now() - interval '10 days' expression was
replaced with 'now'::timestamptz - interval '10 days'. However, care
would need to be taken to ensure the plan is never prepared since
'now' is evaluated during parse. The same care must be taken when
creating views, functions, stored procedures and the like.

The planner will just estimate the selectivity of now() - interval '10
days'  by using DEFAULT_INEQ_SEL, which is 0.3333333333333333, so it
thinks it'll get 1/3rd of the table.  Using 'now' will allow the
planner to lookup actual statistics on that column which will likely
give a much better estimate, which by the looks of it, likely will
result in one of those BRIN index being used.