Cassandra 6 adds ACID transactions via Accord — we test all four options

The road to ACID transactions in Cassandra 6

Cassandra 6.0 is set to introduce Accord, a transactional protocol bringing ACID guarantees to the open-source database. We set up a three-node cluster on the pre-release branch and tested four transactional options: plain updates, BATCH, lightweight transactions (LWT), and Accord. Plain updates violated the balance invariant 939 times in one run; BATCH mostly held, but occasionally produced inconsistent sums due to timestamp collisions. Accord, the new protocol, aims to fix these issues with full ACID semantics.