Thanks a lot for your comments. This mailing list is truly *the *definitive guide to Cassandra *. * The knowledge transferred here is invaluable. So just wanted to give a big shout out to anyone who is helping out here.
Regards, On Thu, May 30, 2019 at 6:10 PM Jon Haddad <j...@jonhaddad.com> wrote: > Yep. I would *never* use mean when it comes to performance to make any > sort of decisions. I prefer to graph all the p99 latencies as well as the > max. > > Some good reading on the topic: > https://bravenewgeek.com/everything-you-know-about-latency-is-wrong/ > > On Thu, May 30, 2019 at 7:35 AM Chris Lohfink <clohfin...@gmail.com> > wrote: > >> For what it is worth, generally I would recommend just using the mean vs >> calculating it yourself. It's a lot easier and averages are meaningless for >> anything besides trending anyway (which is really what this is useful for, >> finding issues on the larger scale), especially with high volume clusters >> so the loss in accuracy kinda moot. Your average for local reads/writes >> will almost always be sub millisecond but you might end up having 500 >> millisecond requests or worse that the mean will hide. >> >> Chris >> >> On Thu, May 30, 2019 at 6:30 AM shalom sagges <shalomsag...@gmail.com> >> wrote: >> >>> Thanks for your replies guys. I really appreciate it. >>> >>> @Alain, I use Graphite for backend on top of Grafana. But the goal is to >>> move from Graphite to Prometheus eventually. >>> >>> I tried to find a direct way of getting a specific Latency metric in >>> average and as Chris pointed out, then Mean value isn't that accurate. >>> I do not wish to use the percentile metrics either, but a single latency >>> metric like the *"Local read latency" *output in nodetool tablestats. >>> Looking at the code of nodetool tablestats, it seems that C* also >>> divides *ReadTotalLatency.Count* with *ReadLatency.Count *to get the >>> latency result. >>> >>> So I guess I will have no choice but to run the calculation on my own >>> via Graphite: >>> >>> divideSeries(averageSeries(keepLastValue(nonNegativeDerivative($env.path.to.host.$host.org_apache_cassandra_metrics.Table.$ks.$cf.ReadTotalLatency.Count))),averageSeries(keepLastValue(nonNegativeDerivative($env.path.to.host.$host.org_apache_cassandra_metrics.Table.$ks.$cf.ReadLatency.Count)))) >>> >>> Does this seem right to you? >>> >>> Thanks! >>> >>> On Thu, May 30, 2019 at 12:34 AM Paul Chandler <p...@redshots.com> >>> wrote: >>> >>>> There are various attributes under >>>> org.apache.cassandra.metrics.ClientRequest.Latency.Read these measure the >>>> latency in milliseconds >>>> >>>> Thanks >>>> >>>> Paul >>>> www.redshots.com >>>> >>>> > On 29 May 2019, at 15:31, 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! >>>> > >>>> > >>>> >>>> >>>> --------------------------------------------------------------------- >>>> To unsubscribe, e-mail: user-unsubscr...@cassandra.apache.org >>>> For additional commands, e-mail: user-h...@cassandra.apache.org >>>> >>>>