To answer your question org.apache.cassandra.metrics:type=Table,name=ReadTotalLatency can give you the total local read latency in microseconds and you can get the count from the Latency read metric.
If you are going to do that be sure to do it on the delta from previous query (new - last) for both total latency and counter or else you will slowly converge to a global average that will almost never change as the quantity of reads simply removes outliers. The mean attribute of the Latency metric you mentioned will give you an approximation for this actually as its taking the total/count of a decaying histogram of the latencies. It will however be even less accurate than using the deltas since the bounds of the decaying wont necessarily match up with your reading intervals and histogram introduces a worst case 20% round up. Even with using deltas though this will hide outliers, you could end up with really bad queries that don't even show up as a tick on your graph (although *generally* it will). Chris On Wed, May 29, 2019 at 9:32 AM shalom sagges <shalomsag...@gmail.com> wrote: > Hi All, > > I'm creating a dashboard that should collect read/write latency metrics on > C* 3.x. > In older versions (e.g. 2.0) I used to divide the total read latency in > microseconds with the read count. > > Is there a metric attribute that shows read/write latency without the need > to do the math, such as in nodetool tablestats "Local read latency" output? > I saw there's a Mean attribute in org.apache.cassandra.metrics.ReadLatency > but I'm not sure this is the right one. > > I'd really appreciate your help on this one. > Thanks! > > >
