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From "ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-16296) Reverse scan performance degrades when scanner cache size matches page filter size
Date Mon, 01 Aug 2016 07:49:20 GMT

     [ https://issues.apache.org/jira/browse/HBASE-16296?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

ramkrishna.s.vasudevan updated HBASE-16296:
-------------------------------------------
    Attachment: PAgefilter.patch

Attaching a simple UT to show the difference with page filter as list and page filter stand
alone. This is not a perf test. It allows to track the flow in the HRegion layer. 
{code}
+    //FilterList list = new FilterList(new PageFilter(5));
+    scan.setFilter(new PageFilter(5));
{code}
The above line can be commented out to check with filterList. The final result may be same
but what are the extra things that the flow does with FilterList can be debugged.

> Reverse scan performance degrades when scanner cache size matches page filter size
> ----------------------------------------------------------------------------------
>
>                 Key: HBASE-16296
>                 URL: https://issues.apache.org/jira/browse/HBASE-16296
>             Project: HBase
>          Issue Type: Bug
>            Reporter: James Taylor
>         Attachments: 16296-MAYBE-v2.txt, 16296-MAYBE.txt, PAgefilter.patch, generatedata-snippet.java,
repro-snippet.java
>
>
> When a reverse scan is done, the server seems to not know it's done when the scanner
cache size matches the number of rows in a PageFilter. See PHOENIX-3121 for how this manifests
itself. We have a standalone, pure HBase API reproducer too that I'll attach (courtesy of
[~churromorales] and [~mujtabachohan]).



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