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From "Brandon Williams (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-7273) expose global ColumnFamily metrics
Date Tue, 17 Jun 2014 17:38:03 GMT


Brandon Williams commented on CASSANDRA-7273:

bq. I was trying to say that some metrics can be meaningless if combined together. For example,
95%tile of global sstables per read can shadow certain column family's high sstable read.
Or bloom filter false positive ratio. If one is high and the other is low, then the global
average cannot tell certain CF has low fp ratio. (Correct me if I'm wrong.)

This was my exact reasoning as well, but [] convinced that in practice,
it actually was helpful.  Keep in mind though this isn't an average, just another histogram
with totals.

bq. Also, there already node level latency metrics in StorageProxy, so I don't feel the need
for one in global CF.

SP latency is different from local latency though.

> expose global ColumnFamily metrics
> ----------------------------------
>                 Key: CASSANDRA-7273
>                 URL:
>             Project: Cassandra
>          Issue Type: New Feature
>            Reporter: Richard Wagner
>            Assignee: Brandon Williams
>            Priority: Minor
>              Labels: lhf
>             Fix For: 1.2.17
>         Attachments: 7273-2_1_branch-v1.txt
> It would be very useful to have cassandra expose ColumnFamily metrics that span all column
families. A general purpose cassandra monitoring system built up around the current ColumnFamily
metrics really only has a couple of choices right now: publish metrics for all column families
or fetch metrics for all column families, aggregate them and then publish the aggregated metrics.
The first can be quite expensive for the downstream monitoring system and the second is a
piece of work that it seems is better pushed into cassandra itself.
> Perhaps these global ColumnFamily metrics could be published under a name of:
> org.apache.cassandra.metrics:type=(ColumnFamily|IndexColumnFamily),name=(Metric name)
> (Same as existing ColumnFamily metrics, but with no keyspace or scope.)

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