The reason we want to KISS is to ensure a solid, robust, and performant layer of storage, that other projects can use to build their transactional versions, etc.

One can take Badger and build a transactional layer above it, and it would still be below the application layer.

> The reason we want to KISS is to ensure a solid, robust, and performant layer of storage, that other projects can use to build their transactional versions, etc.

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.

It's not. The comparison is using the same APIs as provided by LevelDB/RocksDB. Not the transactional ones mentioned below.

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;

Why would one want to though? (edit) as in why choose this and invest hundreds (thousands?) of development hours doing so. What ROI would support this?

Because you were already committed to building a database yourself, so RockDB saves you time in building the base layer.

Transaction support comes with a set of performance compromises, and different companies may want to make different compromises.