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From Mark Reddy <mark.l.re...@gmail.com>
Subject Re: What time range does nodetool cfhistograms use?
Date Sun, 16 Nov 2014 18:05:22 GMT
Hi Clint,

The values of SSTables, Write Latency and Read Latency will be reset on
node start/restart and after running the cfhistograms command itself.

The values of Row Size and Column Count are calculated at startup and
then re-evaluated during compaction.


Mark


On 16 November 2014 17:12, Clint Kelly <clint.kelly@gmail.com> wrote:

> Hi all,
>
> Over what time range does "nodetool cfhistograms" operate?
>
> I am using Cassandra 2.0.8.39.
>
> I am trying to debug some very high 95th and 99th percentile read
> latencies in an application that I'm working on.
>
> I tried running nodetool cfhistograms to get a flavor for the
> distribution of read latencies and also to see how many SSTables our
> reads are using, and I saw different results yesterday versus this
> morning, so I assume the time window is fairly tight (like an hour or
> so).   I vaguely recall Aaron Morton talking about this during the
> training course I took at Cassandra Summit, but I cannot find my notes
> and I think the behavior of the tool with regard to time windows
> changed from version to version.
>
> Thanks!
>
> -Clint
>

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