On 30 Oct 2014 14:49, "Shawn Heisey" <apa...@elyograg.org> wrote:
> In order to see a gain in performance from multiple shards per server, > the server must have a lot of CPUs and the query rate must be fairly > low. If the query rate is high, then all the CPUs will be busy just > handling simultaneous queries, so putting multiple shards per server > will probably slow things down. When query rate is low, multiple CPUs > can handle each shard query simultaneously, speeding up the overall query. Except that your query latency isn't always CPU bound, there's a significant IO bound portion as well. I wouldn't go so far as to say that will large query volumes you shouldn't use multiple shards -- finally comes down to how many shards a machine can handle under peak load, it could depend on CPU/IO/GC pressure.. We have multiple shards on a machine under heavy query load for example. The only real way is to benchmark this and see.. > Thanks, > Shawn >
