Can't you, though? I think I've seen several apps doing it, making the set-up and administration of the cluster abstracted away and transparent to the user (I c

Can't you, though? I think I've seen several apps doing it, making the set-up and administration of the cluster abstracted away and transparent to the user (I can think of KDE's Akonadi suite for instance). That doesn't make the whole DB be contained in a single file, sure, but PG can then serve as the data backend of a versatile lot of applications