> (1) Because SQLite is just a function call whereas PostgreSQL is a round-trip message to a separate server process, MRigger was able to run many more test cas

> (1) Because SQLite is just a function call whereas PostgreSQL is a round-trip message to a separate server process, MRigger was able to run many more test cases per second on SQLite. Yea, that made it harder in the past for other test tooling too. IIRC Greg Stark fuzzed our regex library and had to fight against the more complicated interaction due to client / server to make that work. Ended up finding quite a few things... > (3) SQLite has much stronger backwards compatibility guarantees than PostgreSQL. We have to continue to support design errors made decades ago, whereas PostgreSQL gets to walk away from their poor design choices with each major release. For this reason, SQLite is rather more complicated than you might imagine. FWIW, we (pg devs) are pretty hesitant to break backward compat. Sure, each release has a few things, but it's usually pretty corner case-y stuff. Check e.g. the list for the upcoming v13: https://www.postgresql.org/docs/13/release-13.html https://www.postgresql.org/docs/13/release-13.html There's a lot of significant design errors we're continuing to support just because it'd be too painful to break compat.