Strata

A disk-backed B+Tree with a buffer pool, an LSM tree with compaction, a binary write-ahead log with redo/undo recovery, snapshot-isolation MVCC, a two-phase lock manager with deadlock detection, a hand-written SQL parser, a cost-based optimizer with join reordering, a vectorized executor, Raft consensus and a shard router.

nanosql is the single, explicit exception to the isolation rule: it imports all ten as real package dependencies and turns them into a transactional SQL engine with a REPL and a DB-API driver. No SQLite, DuckDB or Postgres anywhere in the stack — not even in the tests.