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https://issues.apache.org/jira/browse/MAPREDUCE-6012?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14102652#comment-14102652
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Hudson commented on MAPREDUCE-6012:
-----------------------------------
FAILURE: Integrated in Hadoop-Hdfs-trunk #1842 (See
[https://builds.apache.org/job/Hadoop-Hdfs-trunk/1842/])
MAPREDUCE-6012. DBInputSplit creates invalid ranges on Oracle. (Wei Yan via
kasha) (kasha:
http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1618694)
* /hadoop/common/trunk/hadoop-mapreduce-project/CHANGES.txt
*
/hadoop/common/trunk/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/lib/db/OracleDBRecordReader.java
*
/hadoop/common/trunk/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/test/java/org/apache/hadoop/mapreduce/lib/db/TestDbClasses.java
> DBInputSplit creates invalid ranges on Oracle
> ---------------------------------------------
>
> Key: MAPREDUCE-6012
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-6012
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Affects Versions: 1.2.1, 2.4.1
> Reporter: Julien Serdaru
> Assignee: Wei Yan
> Fix For: 1.3.0, 2.6.0
>
> Attachments: HADOOP-9530.patch, MAPREDUCE-6012-2-branch2.patch,
> MAPREDUCE-6012-branch-1.patch
>
>
> The DBInputFormat on Oracle does not create valid ranges.
> The method getSplit line 263 is as follows:
> split = new DBInputSplit(i * chunkSize, (i * chunkSize) +
> chunkSize);
> So the first split will have a start value of 0 (0*chunkSize).
> However, the OracleDBRecordReader, line 84 is as follows:
> if (split.getLength() > 0 && split.getStart() > 0){
> Since the start value of the first range is equal to 0, we will skip the
> block that partitions the input set. As a result, one of the map task will
> process the entire data set, rather than the partition.
> I'm assuming the fix is trivial and would involve removing the second check
> in the if block.
> Also, I believe the OracleDBRecordReader paging query is incorrect.
> Line 92 should read:
> query.append(" ) WHERE dbif_rno > ").append(split.getStart());
> instead of (note > instead of >=)
> query.append(" ) WHERE dbif_rno >= ").append(split.getStart());
> Otherwise some rows will be ignored and some counted more than once.
> A map/reduce job that counts the number of rows based on a predicate will
> highlight the incorrect behavior.
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