One can take Badger and build a transactional layer above it, and it would still be below the application layer.
Then comparing it to Rocks DB is unfair (infact title of this post is misleading). Stuff like transactions and MVCC is way complicated than it sounds.
TransactionDB* txn_db; Status s = TransactionDB::Open(options, path, &txn_db);
Transaction* txn = txn_db->BeginTransaction(write_options, txn_options); s = txn->Put(“key”, “value”); s = txn->Delete(“key2”); s = txn->Merge(“key3”, “value”); s = txn->Commit(); delete txn;
Transaction support comes with a set of performance compromises, and different companies may want to make different compromises.