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Posted to issues@hbase.apache.org by "asha koshti (JIRA)" <ji...@apache.org> on 2013/08/02 13:31:49 UTC

[jira] [Commented] (HBASE-5821) Incorrect handling of null value in Coprocessor aggregation function min()

    [ https://issues.apache.org/jira/browse/HBASE-5821?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13727590#comment-13727590 ] 

asha koshti commented on HBASE-5821:
------------------------------------

Even i am facing the issue in using coprocessor for doing sum.

    AggregationClient aClient = new AggregationClient(conf);
final ColumnInterpreter<Long, Long> ci = new LongColumnInterpreter();
Scan scan = new Scan();
scan.addColumn(Bytes.toBytes("info"),Bytes.toBytes("hits"));
long sum = aClient.sum(Bytes.toBytes("demo"), ci, scan);
                
> Incorrect handling of null value in Coprocessor aggregation function min()
> --------------------------------------------------------------------------
>
>                 Key: HBASE-5821
>                 URL: https://issues.apache.org/jira/browse/HBASE-5821
>             Project: HBase
>          Issue Type: Bug
>          Components: Coprocessors
>    Affects Versions: 0.92.1
>            Reporter: Maryann Xue
>            Assignee: Maryann Xue
>             Fix For: 0.92.2
>
>         Attachments: HBASE-5821.patch
>
>
> Both in AggregateImplementation and AggregationClient, the evaluation of the current minimum value is like:
> min = (min == null || ci.compare(result, min) < 0) ? result : min;
> The LongColumnInterpreter takes null value is treated as the least value, while the above expression takes min as the greater value when it is null. Thus, the real minimum value gets discarded if a null value comes later.
> max() could also be wrong if a different ColumnInterpreter other than LongColumnInterpreter treats null value differently (as the greatest).

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