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https://issues.apache.org/jira/browse/HIVE-12063?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14968082#comment-14968082
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Xuefu Zhang commented on HIVE-12063:
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Thanks, Szehon. Please note, this is actually not that far from my original
thought in HIVE-7373. My point there was that we shouldn't append zeros or
trimming trailing zeros. The patch here doesn't append zeros internally, but
mainly formatting output according to the output schema. (HIVE-7373 failed in
this because it changed the internal representation.) This is in line with
other DBs, though I'm not aware of any SQL standard on this. Yes, I said that
the practice of outputting with appending zeros was questionable, but it makes
sense in Hive's case as Hive aggressively trims 0.0, 0.00, 0.000000 etc all the
way to 0, which is too confusing.
BTW, all vectorization tests passed. [~jdere] or [~hagleitn], please review and
comment. Thanks.
> Pad Decimal numbers with trailing zeros to the scale of the column
> ------------------------------------------------------------------
>
> Key: HIVE-12063
> URL: https://issues.apache.org/jira/browse/HIVE-12063
> Project: Hive
> Issue Type: Improvement
> Components: Types
> Affects Versions: 0.14.0, 1.0.0, 1.2.0, 1.1.0, 0.13
> Reporter: Xuefu Zhang
> Assignee: Xuefu Zhang
> Attachments: HIVE-12063.1.patch, HIVE-12063.2.patch, HIVE-12063.patch
>
>
> HIVE-7373 was to address the problems of trimming tailing zeros by Hive,
> which caused many problems including treating 0.0, 0.00 and so on as 0, which
> has different precision/scale. Please refer to HIVE-7373 description.
> However, HIVE-7373 was reverted by HIVE-8745 while the underlying problems
> remained. HIVE-11835 was resolved recently to address one of the problems,
> where 0.0, 0.00, and so on cannot be read into decimal(1,1).
> However, HIVE-11835 didn't address the problem of showing as 0 in query
> result for any decimal values such as 0.0, 0.00, etc. This causes confusion
> as 0 and 0.0 have different precision/scale than 0.
> The proposal here is to pad zeros for query result to the type's scale. This
> not only removes the confusion described above, but also aligns with many
> other DBs. Internal decimal number representation doesn't change, however.
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