That was my thought, too. If you need ACID transactions, use an ACID database. There are rather a lot of them. And then mirror the data out to Cassandra after the fact, if you need it there. Ironically, Cassandra may not be the source of truth!
Way back in the stone age, MySQL did not yet have ACID transactions. They got them about the same time they stopped bragging about how much faster they were than Oracle, but I digress. Anyway, I had to write a bunch of transactional code around it. Drove the dba and me nuts. We begged for Sybase (we both knew it well), but the startup CTO was an open source purist and hated his first contact with the Sybase sales machine.
Way back in the stone age, MySQL did not yet have ACID transactions. They got them about the same time they stopped bragging about how much faster they were than Oracle, but I digress. Anyway, I had to write a bunch of transactional code around it. Drove the dba and me nuts. We begged for Sybase (we both knew it well), but the startup CTO was an open source purist and hated his first contact with the Sybase sales machine.
Eventually they folded, and the point was moot.