# ESRally Metrics Definition

**URL:** <https://discuss.elastic.co/t/esrally-metrics-definition/101850>\
**Category:** Elasticsearch\
**Tags:** rally\
**Created:** [September 26, 2017, 1:36pm UTC](https://discuss.elastic.co/t/esrally-metrics-definition/101850 "2017-09-26T13:36:39Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![sanketshinde](https://avatars.discourse-cdn.com/v4/letter/s/b5ac83/32.png) [@sanketshinde](https://discuss.elastic.co/u/sanketshinde)\
**Post date:** [September 26, 2017, 1:36pm UTC](https://discuss.elastic.co/t/esrally-metrics-definition/101850/1 "2017-09-26T13:36:39Z")

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I am working with ESRally and would like to understand what the various metrics mean. I tried reading the documentation provided here: [http://esrally.readthedocs.io/en/latest/summary\_report.html](http://esrally.readthedocs.io/en/latest/summary_report.html), but it does not convey details such as what segment merging is, what is the flush time and why are these values even chosen as a metric to indicate performance.

Any pointers?

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**Author:** ![danielmitterdorfer](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/danielmitterdorfer/32/110510_2.png) [@danielmitterdorfer](https://discuss.elastic.co/u/danielmitterdorfer)\
**Post date:** [September 26, 2017, 2:29pm UTC](https://discuss.elastic.co/t/esrally-metrics-definition/101850/2 "2017-09-26T14:29:41Z")

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Hi @sanketshinde,

to the meaning of the individual metrics: the documentation only explains on a high-level and admittedly assume a detailed understanding of the inner workings of Elasticsearch. Btw, there is also [http://esrally.readthedocs.io/en/stable/metrics.html](http://esrally.readthedocs.io/en/stable/metrics.html) that explains the raw metrics that Rally uses to create the summary report.

IMHO the primary metrics to look at are the request-related metrics: throughput (e.g. for bulk indexing operations) and service time or latency (for latency-sensitive operations like queries). The other metrics serve as secondary metrics to better understand where Elasticsearch spent time during indexing: was it busy [merging a lot of segments](https://www.elastic.co/guide/en/elasticsearch/guide/2.x/merge-process.html), where merges throttled for a long time (disk issues?) etc. I think these can just serve as a first indication and once you see high values you need to dig further anyway with other tools like `iostat`, `vmstat`, a Java profiler, ... .

Daniel

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**Author:** ![sanketshinde](https://avatars.discourse-cdn.com/v4/letter/s/b5ac83/32.png) [@sanketshinde](https://discuss.elastic.co/u/sanketshinde)\
**Post date:** [September 29, 2017, 9:29am UTC](https://discuss.elastic.co/t/esrally-metrics-definition/101850/3 "2017-09-29T09:29:57Z")

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Thanks for the pointers.

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [October 27, 2017, 9:30am UTC](https://discuss.elastic.co/t/esrally-metrics-definition/101850/4 "2017-10-27T09:30:43Z")

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