Comment by eloff

I've been developing high performance databases for the last five years off and on. This article is right on the money. It's tough to beat MVCC for a database that wants isolated concurrent transactions. Append only designs seem attractive, but they don't actually help much with write throughput on SSDs (but avoiding in-place updates does, due to erase blocks.) And they often require writing much more information. E.g. writing 100 bytes in LMDB, which is an append only btree, requires copying all pages from the root to the leaf and writing them all out, typically 64k or more. Writing 100 bytes to a transaction log or WAL costs about 100 bytes. There's a huge write amplification going on.