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Date: Tue, 22 Sep 2015 22:19:05 +0000 (UTC)
From: "Hudson (JIRA)" <jira@apache.org>
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Subject: [jira] [Commented] (HBASE-14397) PrefixFilter doesn't filter all
 remaining rows if the prefix is longer than rowkey being compared
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    [ https://issues.apache.org/jira/browse/HBASE-14397?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14903557#comment-14903557 ] 

Hudson commented on HBASE-14397:
--------------------------------

FAILURE: Integrated in HBase-1.3-IT #175 (See [https://builds.apache.org/job/HBase-1.3-IT/175/])
HBASE-14397 Revert pending review comments (tedyu: rev 992856c11dbe6551807931c6a5a31efacb9ec80b)
* hbase-client/src/main/java/org/apache/hadoop/hbase/filter/PrefixFilter.java


> PrefixFilter doesn't filter all remaining rows if the prefix is longer than rowkey being compared
> -------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-14397
>                 URL: https://issues.apache.org/jira/browse/HBASE-14397
>             Project: HBase
>          Issue Type: Improvement
>          Components: Filters
>    Affects Versions: 2.0.0
>            Reporter: Jianwei Cui
>            Assignee: Jianwei Cui
>            Priority: Minor
>         Attachments: HBASE-14397-trunk-v1.patch
>
>
> The PrefixFilter will filter rowkey as:
> {code}
>   public boolean filterRowKey(Cell firstRowCell) {
>     ...
>     int length = firstRowCell.getRowLength();
>     if (length < prefix.length) return true; // ===> return directly if the prefix is longer
>     ....
>     if ((!isReversed() && cmp > 0) || (isReversed() && cmp < 0)) {
>       passedPrefix = true;
>     }
>     filterRow = (cmp != 0);
>     return filterRow;
>   }
> {code}
> If the prefix is longer than the current rowkey, PrefixFilter#filterRowKey will filter the rowkey directly without comparing, so that won't set 'passedPrefix' flag even the current row is larger than the prefix.
> For example, if there are three rows 'a', 'b' and 'c' in the table, and we issue a scan request as:
> {code}
> hbase(main):001:0> scan 'test_table', {STARTROW => 'a', FILTER => "(PrefixFilter ('aa'))"}
> {code}
> The region server will check the three rows before returning.  In our production, the user issue a scan with a PrefixFilter. The prefix is longer than the rowkeys of following millions of rows, so the region server will continue to check rows until hit a rowkey longer than the prefix. This make the client easily timeout. To fix this case, it seems we need to compare the prefix with the rowkey every serveral rows even when the prefix is longer.


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