I didn't know about this cfhistograms thing, very nice!
From: user@cassandra.apache.org
Subject: Re: Unexplained query slowness
Have a look at your column family histograms (nodetool cfhistograms iirc), if
you notice things like a very long tail, a double hump or outliers it would
indicate
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