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https://issues.apache.org/jira/browse/HIVE-16311?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15958772#comment-15958772
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Matt McCline edited comment on HIVE-16311 at 4/6/17 12:52 PM:
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Fundamental to the OldHiveDecimal and new HiveDecimal is the idea of a floating
scale during from various calculations (and without any trailing fractional
zeroes) and the use of enforcePrecisionScale afterwards to adjust a decimal to
fit a precision/scale and later toFormatString to add trailing fractional
zeroes in the display. So, trying to "remember" the original number of
trailing zeroes is not going to work and not part of the current design. (See
HiveDecimal's header comments).
So the new member fastTrailingZero needs to be removed.
was (Author: mmccline):
Fundamental to the OldHiveDecimal and new HiveDecimal is the idea of a floating
scale during from various calculations (and without any trailing fractional
zeroes) and the use of enforcePrecisionScale afterwards. So, trying to
"remember" the original number of trailing zeroes is not going to work and not
part of the current design. (See HiveDecimal's header comments).
So the new member fastTrailingZero needs to be removed.
> 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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