The change here breaks backwards compatibility a tiny bit:

• Use UPSERT (aka INSERT ... ON CONFLICT SET) in .upsert() and .upsert_all() when available #652

I'm going to ship it as a 4.0 alpha first to exercise it a bit more.

If I'm doing a 4.0 there may be other backwards-incompatible changes I want to sneak in too.

Backwards incompatible changes

• Use UPSERT (aka INSERT ... ON CONFLICT SET) in .upsert() and .upsert_all() when available #652
• db.table() should only return tables, add db.view() #657

Other changes for 4.0 (not necessarily backwards incompatible)

• Whether or not a table remembers or detects its primary key is confusing and messy #655