I am sorry if it's too basic and you already looked at that, but the first thing I would ask would be the data model.
What data model are you using (how is your data partitioned)? What queries are you running? If you are using ALLOW FILTERING, for instance, it will be very easy to say why it's slow. Most times people get slow queries in Cassandra they are using the wrong data model. []s From: user@cassandra.apache.org Subject: Re:Unexplained query slowness Our Cassandra database just rolled to live last night. I’m looking at our query performance, and overall it is very good, but perhaps 1 in 10,000 queries takes several hundred milliseconds (up to a full second). I’ve grepped for GC in the system.log on all nodes, and there aren’t any recent GC events. I’m executing ~500 queries per second, which produces negligible load and CPU utilization. I have very minimal writes (one every few minutes). The slow queries are across the board. There isn’t one particular query that is slow. I’m running 2.0.12 with SSD’s. I’ve got a 10 node cluster with RF=3. I have no idea where to even begin to look. Any thoughts on where to start would be greatly appreciated. Robert
