On Tue, Sep 15, 2015 at 7:44 AM, Tom van den Berge < tom.vandenbe...@gmail.com> wrote:
> Read queries on a secondary index are somehow causing an excessively high > CPU load on all nodes in my DC. > ... > What really surprised me is that executing a single query on this > secondary index makes the "Local read count" in the cfstats for the index > go up with almost 200000! When doing the same query on one of my "good" > nodes, it only increases with a small number, as I would expect. > > Could it be that the use of vnodes is causing these problems? > I am not too surprised to hear of this performance degradation. Yes, it is relatively likely to be the use of vnodes which is causing this problem. You could verify by having one of your nodes use 64 vnodes instead of the default 256... you will get less even distribution with current vnode random allocation, but you will pay less of a penalty for having multiple ranges... =Rob
