In case anybody wants estimates of medians, Mahout has some easily extractable code to compute medians and first and third quartiles without keeping lots of data around. As a side effect, it computes averages and standard deviations as well.
I don't think that such a small thing as this warrants an entire dependency and would be happy to extract the code in question if anybody wants this. Just point me at a JIRA where I should stick it. On Tue, May 24, 2011 at 10:17 AM, Stack <[email protected]> wrote: > Tim: > > You should get a copy of Lars' book. Then you'd know what the below > are (smile). > > Quoting: > > "A commonly used metric in HBase is called time varying rate, which > not only tracks the number of events, but also how long each event > took to complete. A TVR exposes four values. [Below] shows the > values and their meanings. > > Value Name Short Description > Number Operations NumOps The actual number of events since the last > poll > Minimum Time MniTime The shortest time reported for an event > to complete > Maximum Time MaxTime The longest time reported for an event to > complete > Average Time AvgTime The average time for completing > events...sum of times per event divided by number of events" > > Our metrics need a bit of a revamp so file issues on stuff that seems off > Tim. > > St.Ack > > On Mon, May 23, 2011 at 10:39 AM, Tim Sell <[email protected]> wrote: > > I am collecting hbase stats from jmx. > > > > Here's an example of the compaction stats from one of the region > servers... > > > > compactionQueueSize 0 > > compactionSizeAvgTime 19349729 > > compactionSizeMaxTime 566512933 > > compactionSizeMinTime 0 > > compactionSizeNumOps 8 > > compactionTimeAvgTime 83 > > compactionTimeMaxTime 1300 > > compactionTimeMinTime 0 > > compactionTimeNumOps 8 > > > > What does NumOps of compactionSize and compactionTime mean? is that > > the total number of compactions ever? > > > > Also, having a time suffix for compactionSize seems confusing. It > > seems an artifact of this: > > > > protected final PersistentMetricsTimeVaryingRate compactionTime = > > new PersistentMetricsTimeVaryingRate("compactionTime", registry); > > protected final PersistentMetricsTimeVaryingRate compactionSize = > > new PersistentMetricsTimeVaryingRate("compactionSize", registry); > > >
