Nicola Mauri <nicola.mauri@saga.it> writes:
>> What do you have max_fsm_pages set to?
> Currently, max_fsm_pages=20000
> Running VACUUM VERBOSE reports:
> NOTICE: number of page slots needed (237312) exceeds max_fsm_pages (20000)
> HINT: Consider increasing the configuration parameter "max_fsm_pages" to a value over 237312.
Yup, there's your problem (or a huge chunk of it anyway).
> Is this measurement reliable?
> We are considering to set: max_fsm_pages=400000
> Could this have some sort of impact?
It will require a slightly larger shared-memory segment than you have
now.
regards, tom lane