On Fri, Sep 19, 2014 at 12:41 PM, Jay Patel <pateljay3...@gmail.com> wrote:
> > Btw, there is no data in the table. Table is empty. Query is fired on the > empty table. > This is actually the worst case for secondary index lookups. > > From the tracing ouput, I don't understand why it's doing multiple scans > on one node. With non-vnode, there is only one scan per node & same query > works fine. > > If you look at the output1.txt attached earlier, coordinator is firing > index scan on a given node (for example, 192.168.51.22 in the below snippet > from output1.txt) multiple times for different token ranges. Why can't it > fire only one time? With non-vnode, it's only one time & query comes back > very fast. It will merge requests to neighboring ranges when the same node is a replica for both of them. Without vnodes, this usually results in all ranges for a node being merged. With vnodes, merging still happens, but not all ranges can be merged. -- Tyler Hobbs DataStax <http://datastax.com/>
