You can use query tracing to check what is happening. Also you fire jconsole/JavaVisualVM and push out some metrics like the 99th read Beans for that column family. A simpler check is using cfstats and look for weird numbers (high number sstables, if you are deleting check how much tombstones per scan, etc).
Another is checking if compactions are not running when you query. Opscenter can provide some graphs and help out. Regards, Carlos Juzarte Rolo Cassandra Consultant Pythian - Love your data rolo@pythian | Twitter: cjrolo | Linkedin: *linkedin.com/in/carlosjuzarterolo <http://linkedin.com/in/carlosjuzarterolo>* Tel: 1649 www.pythian.com On Wed, Feb 25, 2015 at 4:32 PM, Robert Wille <rwi...@fold3.com> wrote: > 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 > > -- --
