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From "Jarek Jarcec Cecho (JIRA)" <j...@apache.org>
Subject [jira] [Created] (SQOOP-603) Support small intervals in IntegerSplitter implementation
Date Fri, 14 Sep 2012 05:57:07 GMT
Jarek Jarcec Cecho created SQOOP-603:
----------------------------------------

             Summary: Support small intervals in IntegerSplitter implementation
                 Key: SQOOP-603
                 URL: https://issues.apache.org/jira/browse/SQOOP-603
             Project: Sqoop
          Issue Type: Improvement
    Affects Versions: 1.4.2
            Reporter: Jarek Jarcec Cecho
            Assignee: Jarek Jarcec Cecho
             Fix For: 1.4.3


IntegerSplitter is currently creating splits of following nature:

{code}
minimal value <= x < splitPoint1
splitPoint1 <= x < splitPoint2
...
splitPointN <= x <= maximal value
{code}

Please notice that upper bound is always with using condition "<" with exception of the
last split that is using condition "<=". This is perfectly fine when creating reasonable
amount of splits on very huge interval.

This approach will however cause issues on very small intervals. For example following splits
will be created on interval [0, 5] with 5 splits:

* 0 <= x < 1
* 1 <= x < 2 
* 2 <= x < 3 
* 3 <= x < 4 
* 4 <= x <= 5

Notice that all splits have equal count of numbers except the last one having two numbers
- 4 and 5. This becomes very huge issue when for example user needs to create one split per
one partition as one mapper will end up with moving two partitions and thus entire job will
take twice as long as the other ones.

Jarcec

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