[hansvm]

> Traversing a medium depth DAG with a million nodes to find orphaned nodes takes less than a second on average hardware.

Unless you have an abnormally high edge count that sounds super slow to me. Even accounting for metadata overhead and disk page slop you're only reading and processing tens of megabytes, and every algorithm in sight is linear. I'd be surprised if you couldn't get a 2-5x speedup by reading the whole table to RAM in your favorite compiled/jitted language and just traversing it there.

> I have not yet found a situation where nosql databases like leveldb offer an orders of magnitude advantage over SQLite, and SQLite is so much more powerful and robust...

I have no skin in that game, but would some of the nosql solutions not perform significantly better under heavily concurrent insertions and the other workloads they were designed for?