> Oldest transaction : 91891
> Oldest active : 2956068
> Oldest snapshot : 2956068
> Next transaction : 2956086
>
> I guess the gap between Oldest en Next transaction is way too big ? Am I right ? After doing a sweep, the Oldest and Next become equal.

Yes, it is even bigger than "way too big" gap. It is completely
insane. I wonder if your customer did something stupid like set
auto-sweep interval to 0, because with standard setting 20000, gap can't
be so big (unless the oldest transaction is really still alive).

SY, SD.