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https://issues.apache.org/jira/browse/HIVE-13423?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15583055#comment-15583055
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Xuefu Zhang commented on HIVE-13423:
------------------------------------
[~ctang.ma]/[~aihuaxu], as to sacrificing scale for bigger integer part, it
doesn't seem to be a viable option. The precision/scale of the result type of
sum udf is determined statically as result metadata. That is, the result type
of sum(decimal(p, s)) is decimal(p+10, s), which is decided before seeing any
actual data. Thus, at run time when the data is actually processed, we cannot
return the result of decimal( p+10+d, s-d) because the data (result) doesn't
conform to the metadata (type decimal(p+10, s).
Please feel free to check standards or what other dbs are dong. As far as I
know, there is no standard that permits this.
> Handle the overflow case for decimal datatype for sum()
> -------------------------------------------------------
>
> Key: HIVE-13423
> URL: https://issues.apache.org/jira/browse/HIVE-13423
> Project: Hive
> Issue Type: Bug
> Components: Query Processor
> Affects Versions: 2.0.0
> Reporter: Aihua Xu
> Assignee: Aihua Xu
> Attachments: HIVE-13423.1.patch
>
>
> When a column col1 defined as decimal and if the sum of the column overflows,
> we will try to increase the decimal precision by 10. But if it's reaching 38
> (the max precision), the overflow still could happen. Right now, if such case
> happens, the following exception will throw since hive is writing incorrect
> data.
> {noformat}
> Caused by: java.lang.ArrayIndexOutOfBoundsException: 1
> at
> org.apache.hadoop.hive.serde2.lazybinary.LazyBinaryUtils.readVInt(LazyBinaryUtils.java:314)
> ~[hive-exec-2.2.0-SNAPSHOT.jar:2.2.0-SNAPSHOT]
> at
> org.apache.hadoop.hive.serde2.lazybinary.LazyBinaryUtils.checkObjectByteInfo(LazyBinaryUtils.java:219)
> ~[hive-exec-2.2.0-SNAPSHOT.jar:2.2.0-SNAPSHOT]
> at
> org.apache.hadoop.hive.serde2.lazybinary.LazyBinaryStruct.parse(LazyBinaryStruct.java:142)
> ~[hive-exec-2.2.0-SNAPSHOT.jar:2.2.0-SNAPSHOT]
> {noformat}
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