I've asked this to the Crate people before, and not received much in the way of a satisfactory answer. Elasticsearch fundamentally does not provide ACID-style durability guarantees, and Jepsen testing has revealed near-as-makes-no-difference insurmountable problems in replication during partitions. As such I can't wrap my head around why Crate thinks it's safe or even coherent to build a database product on top of it. Even ES core devs make it very clear when you ask (and I have) -- ES should be used as a secondary index, and not as primary data storage.

What gives? What am I not seeing here?