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Date: Wed, 2 Mar 2016 07:38:18 +0000 (UTC)
From: "Heng Chen (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: <JIRA.12946022.1456886194000.191878.1456904298318@Atlassian.JIRA>
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 <JIRA.12946022.1456886194540@arcas>
Subject: [jira] [Updated] (HBASE-15376) ScanNext metric is size-based while
 every other per-operation metric is time based
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     [ https://issues.apache.org/jira/browse/HBASE-15376?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Heng Chen updated HBASE-15376:
------------------------------
    Attachment: HBASE-15376.patch

Make a patch for it. 

{code}
ScanNextTime_num_ops: 4,
ScanNextTime_min: 11,
ScanNextTime_max: 29,
ScanNextTime_mean: 17,
ScanNextTime_25th_percentile: 11,
ScanNextTime_median: 12,
ScanNextTime_75th_percentile: 29,
ScanNextTime_90th_percentile: 29,
ScanNextTime_95th_percentile: 29,
ScanNextTime_98th_percentile: 29,
ScanNextTime_99th_percentile: 29,
ScanNextTime_99.9th_percentile: 29,
ScanNextTime_TimeRangeCount_10-30: 3,
{code}

> 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
>         Attachments: HBASE-15376.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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