I keep hearing Cassandra touted as fast, but I just don't see it. Instacluster brags about 17ms at the 99th percentile being fast, but where I come from that gets you thrown out of the running.[1] The Netflix benchmark linked above sees 10,000 ops/sec/node. Again, not impressive.

Skip to slide 22 of this comparative benchmark with Couchbase Server[2] and you'll see that <5ms latencies at 99% is totally achievable. We can't take too much credit for these stats, most of the blame goes to the fact we use memcached at the front end, and it's been optimized for consistent low-latency for a long time.

I don't want to make this a speed contest, as there are a lot of good things about Cassandra. It just strikes me as odd that people sell Cassandra based on low latency. If you want consistent high-performance, don't use a database that runs on a language virtual machine. There are lots of great reasons to use Cassandra, standout benchmarks aren't one of them.

[1] https://www.instaclustr.com/solution#tco [2] http://www.slideshare.net/renatko/couchbase-performance-benc...