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Interpreting the output of cassandra-stress

Apache Cassandra stress periodically outputs some information pertaining to the tests it is running. Each line reports data for the interval between the last elapsed time and current elapsed time. The interval between lines is controlled by the --progress-interval option and is 10 seconds by default.

  • total reports the total number of operations since the start of the test. 
  • interval_op_rate shows the number of operations performed during the interval.
  • interval_key_rate shows the number of keys/rows read or written during the interval (normally be the same as interval_op_rate unless doing range slices).
  • latency shows the average latency for each operation during that interval.
  • 95th and 99th show latencies in the respective percentile during the interval (e.g., 95% and 99% of the time, the latency was less than this amount). These are only shown in Cassandra 1.2 or later.
  • elapsed is the number of seconds elapsed since the beginning of the test.
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    Phillip Pacheco

    To clarify, latency of the 95th percentile is the 5th column, latency of the 99th percentile is the 6th column.  Elapsed is the 7th column, but it's the 5th column in pre Cassandra 1.2 (breaking my cassandra stress test scripts).

    Thanks for this post

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