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https://issues.apache.org/jira/browse/CASSANDRA-14531?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Matt Byrd reassigned CASSANDRA-14531:
-------------------------------------
Assignee: Matt Byrd
> Only include data owned by the node in totals for repaired, un-repaired and
> pending repair.
> -------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-14531
> URL: https://issues.apache.org/jira/browse/CASSANDRA-14531
> Project: Cassandra
> Issue Type: Improvement
> Components: Metrics, Repair
> Reporter: Matt Byrd
> Assignee: Matt Byrd
> Priority: Minor
> Fix For: 4.x
>
>
> If there is data which is left over from a topology change and is not yet
> cleaned up, it will be included in the total for BytesRepaired,
> BytesUnrepaired or BytesPendingRepair metrics.
> This can distort the total and lead to misleading metrics (albeit
> potentially short-lived).
> As an operator if you wanted to keep track of percent repaired, you might
> not have an accurate idea of the relevant percent repaired under such
> conditions.
> I propose we only include sstables owned by the node in the totals for
> BytesRepaired, BytesUnrepaired, BytesPendingRepair and PercentRepaired. It
> feels more logical to only emit metrics like repaired/un-repaired for data
> which can actually be repaired.
> When an SStable is partially owned by the node, we can compute the size which
> falls within the token-range by binary searching the index for the
> uncompressed offsets.
> We can finally also emit a metric which consists of all the data which is
> not owned by the node.
> This might also be helpful for operators to discover whether there is data
> which is not owned by the node and hence the need to run cleanup.
> On slight complication is that with a large number of sstables and a
> reasonable number of vnodes, computing these values now becomes a bit
> expensive. There is probably a way of keeping some of these metrics updated
> online rather than re-computing periodically, though this might be a bit
> fiddly. Alternately using things like the interval tree or some other
> data-structure might be enough to ensure it performs sufficiently and doesn't
> add undue overhead.
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