Understanding druid monitoring metrics related to queries

Joaquin Navarro

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Dec 11, 2020, 4:33:49 AM12/11/20

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Hello,

I'm configuring my Druid cluster (version 0.19.0) to emit some metrics related to query performance via StatsD. I would like to better understand the meaning of some of the query related metrics:

1. I'm obtaining the query/bytes metric on both Broker and Historical servers, but with different values. What does each metric mean? What is the difference between both?

2. If I execute a query using the Druid Web UI, it generates query/bytes metric on the Historical server, but not on the Broker server. Is that the expected behaviour? Why?

Thank you for you time.

Regards.

Peter Marshall

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Dec 14, 2020, 9:52:34 AM12/14/20

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Hey! I'm not 100% sure - but I suspect it could be showing the data returned per sub-query on each Historical back to the broker - and then the broker query/bytes is the volume returned to the user. I will ask around...

Peter Marshall

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Jan 5, 2021, 7:38:13 AM1/5/21

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Morning Joaquin just tidying up some old emails (!) and yes, query/bytes from the broker indicates the volume returned to the client, whereas query/bytes from the historical is the data from each historical returned to the broker. Do you think the docs might need updating?

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