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https://issues.apache.org/jira/browse/HIVE-9000?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ashutosh Chauhan resolved HIVE-9000.
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Resolution: Invalid
> LAST_VALUE Window function returns wrong results
> ------------------------------------------------
>
> Key: HIVE-9000
> URL: https://issues.apache.org/jira/browse/HIVE-9000
> Project: Hive
> Issue Type: Bug
> Components: PTF-Windowing
> Reporter: Mark Grover
> Priority: Critical
>
> LAST_VALUE Windowing function has been returning bad results, as far as I can
> tell from day 1.
> And, it seems like the tests are also asserting that LAST_VALUE gives the
> wrong result.
> Here's the test output:
> https://github.com/apache/hive/blob/branch-0.14/ql/src/test/results/clientpositive/windowing_navfn.q.out#L587
> The query is:
> {code}
> select t, s, i, last_value(i) over (partition by t order by s) from over10k
> where (s = 'oscar allen' or s = 'oscar carson') and t = 10
> {code}
> The result is:
> {code}
> t s i last_value(i)
> -------------------------------------------------------
> 10 oscar allen 65662 65662
> 10 oscar carson 65549 65549
> {code}
> {{LAST_VALUE( i )}} should have returned 65549 in both records, instead it
> simply ends up returning i.
> Another way you can make sure LAST_VALUE is bad is to verify it's result
> against LEAD(i,1) over (partition by t order by s). LAST_VALUE being last
> value should always be more (in terms of the specified 'order by s') than the
> lead by 1. While this doesn't directly apply to the above query, if the
> result set had more rows, you would clearly see records where lead is higher
> than last_value which is semantically incorrect.
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