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https://issues.apache.org/jira/browse/HBASE-15376?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Enis Soztutar updated HBASE-15376:
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Hadoop Flags: Incompatible change,Reviewed (was: Reviewed)
Release Note:
Removed ScanNext histogram metrics as regionserver level and per-region level
metrics since the semantics is not compatible with other similar metrics (size
histogram vs latency histogram).
Instead, this patch adds ScanTime and ScanSize histogram metrics at the
regionserver and per-region level.
> ScanNext metric is size-based while every other per-operation metric is time
> based
> ----------------------------------------------------------------------------------
>
> Key: HBASE-15376
> URL: https://issues.apache.org/jira/browse/HBASE-15376
> Project: HBase
> Issue Type: Sub-task
> Reporter: Enis Soztutar
> Assignee: Heng Chen
> Fix For: 2.0.0, 1.3.0, 1.4.0
>
> Attachments: HBASE-15376.patch, HBASE-15376_v1.patch,
> HBASE-15376_v3.patch
>
>
> We have per-operation metrics for {{Get}}, {{Mutate}}, {{Delete}},
> {{Increment}}, and {{ScanNext}}.
> The metrics are emitted like:
> {code}
> "Get_num_ops" : 4837505,
> "Get_min" : 0,
> "Get_max" : 296,
> "Get_mean" : 0.2934618155433431,
> "Get_median" : 0.0,
> "Get_75th_percentile" : 0.0,
> "Get_95th_percentile" : 1.0,
> "Get_99th_percentile" : 1.0,
> ...
> "ScanNext_num_ops" : 194705,
> "ScanNext_min" : 0,
> "ScanNext_max" : 18441,
> "ScanNext_mean" : 7468.274651395701,
> "ScanNext_median" : 583.0,
> "ScanNext_75th_percentile" : 583.0,
> "ScanNext_95th_percentile" : 13481.0,
> "ScanNext_99th_percentile" : 13481.0,
> {code}
> The problem is that all of Get,Mutate,Delete,Increment,Append,Replay are time
> based tracking how long the operation ran, while ScanNext is tracking
> returned response sizes (returned cell-sizes to be exact). Obviously, this is
> very confusing and you would only know this subtlety if you read the metrics
> collection code.
> Not sure how useful is the ScanNext metric as it is today. We can deprecate
> it, and introduce a time based one to keep track of scan request latencies.
> ps. Shamelessly using the parent jira (since these seem relavant).
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