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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-11990) Make setting the start and stop row for a specific prefix easier
Date Mon, 22 Sep 2014 18:11:36 GMT

    [ https://issues.apache.org/jira/browse/HBASE-11990?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14143553#comment-14143553
] 

Lars Hofhansl commented on HBASE-11990:
---------------------------------------

This is a pretty constructed case... Yes, each mapper need to scan at least one KeyValue from
its region to determine that it is done, it doesn't scan the whole region.

Note that then with your change you'd also need to adjust getSplits(...) for the inclusive
case, or you might miss the final row.


> Make setting the start and stop row for a specific prefix easier
> ----------------------------------------------------------------
>
>                 Key: HBASE-11990
>                 URL: https://issues.apache.org/jira/browse/HBASE-11990
>             Project: HBase
>          Issue Type: New Feature
>          Components: Client
>            Reporter: Niels Basjes
>         Attachments: 11990v4.txt, HBASE-11990-20140916-v2.patch, HBASE-11990-20140916-v3.patch,
HBASE-11990-20140916-v5.patch, HBASE-11990-20140916-v6.patch, HBASE-11990-20140916.patch,
HBASE-11990-20140917-v7.patch, HBASE-11990-20140919-v8.patch, HBASE-11990-20140921-v9.patch
>
>
> If you want to set a scan from your application to scan for a specific row prefix this
is actually quite hard.
> As described in several places you can set the startRow to the prefix; yet the stopRow
should be set to the prefix '+1'
> If the prefix 'ASCII' put into a byte[] then this is easy because you can simply increment
the last byte of the array. 
> But if your application uses real binary rowids you may run into the scenario that your
prefix is something like 
> {code}{ 0x12, 0x23, 0xFF, 0xFF }{code} Then the increment should be {code}{ 0x12, 0x24
}{code}
> I have prepared a proposed patch that makes setting these values correctly a lot easier.



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