IncrementalIDGeneration object_already_persistent exception

[niniemann]

We've faced some odb::object_already_persistent-exceptions when using the IncrementalIDGeneration. The fix was to load all entities before adding/manipulating anything else. My best guess is that the IncrementalIDGeneration creates IDs that are already taken by objects that were not loaded, though the generation should have everything it needs stored in PrefixAssignedIDs.

[niniemann]

Couldn't reproduce.
@y0urself does your error still occur when with the current master?

[niniemann]

One issue may be that the IncrementalIDGeneration only saves its current state on destruction. I'll take a look at how to improve this -- maybe an update-for-every-new-id is necessary. Could an atomic-increment-and-return of a counter on the database-side be a good idea?