[voidmain]

FoundationDB does interactive transactions.

[atombender]

Last I checked, the entire transaction is built in memory (and famously has a five-second time limit), so while you can make multiple round trips, it's not quite as useful as with other databases.

[richieartoul]

The 5s timeout is annoying sometimes, but it does really support interactive transactions in the exact same sense that PostGres and MySQL do.