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https://issues.apache.org/jira/browse/HIVE-16311?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15958987#comment-15958987
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Matt McCline commented on HIVE-16311:
-------------------------------------
1234567.8901234560/9 is a trailing zero 1234567.8901234560 stripped to
1234567.890123456 divided by 9. But the bigger question is what *result*
decimal precision/scale did Hive choose to do its enforcePrecisionScale and
toFormatString(int formatScale) did Hive choose? What is in the EXPLAIN plan?
(Exact result of division: 137174.21001371733)
> Improve the performance for FastHiveDecimalImpl.fastDivide
> ----------------------------------------------------------
>
> Key: HIVE-16311
> URL: https://issues.apache.org/jira/browse/HIVE-16311
> Project: Hive
> Issue Type: Improvement
> Affects Versions: 2.2.0
> Reporter: Colin Ma
> Assignee: Colin Ma
> Fix For: 3.0.0
>
> Attachments: HIVE-16311.001.patch, HIVE-16311.002.patch,
> HIVE-16311.003.patch, HIVE-16311.004.patch, HIVE-16311.005.patch,
> HIVE-16311.withTrailingZero.patch
>
>
> FastHiveDecimalImpl.fastDivide is poor performance when evaluate the
> expression as 12345.67/123.45
> There are 2 points can be improved:
> 1. Don't always use HiveDecimal.MAX_SCALE as scale when do the
> BigDecimal.divide.
> 2. Get the precision for BigInteger in a fast way if possible.
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