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https://issues.apache.org/jira/browse/KYLIN-6045?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17930102#comment-17930102
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ASF GitHub Bot commented on KYLIN-6045:
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gleonSun opened a new pull request, #2295:
URL: https://github.com/apache/kylin/pull/2295
* Replacement for calcite AggregateMergeRule
> SUM Query Decimal Precision Anomaly
> -----------------------------------
>
> Key: KYLIN-6045
> URL: https://issues.apache.org/jira/browse/KYLIN-6045
> Project: Kylin
> Issue Type: Bug
> Affects Versions: 5.0.0
> Reporter: Guoliang Sun
> Priority: Major
>
> When generating the Spark plan for a query, a `cast` conversion is added for
> the `sum` aggregation in `AggregatePlan.buildAgg`. At this point, the input
> type is the column type, causing the precision of the `cast` to be reduced.
> This results in the query returning `null`.
> h3. Example
> - The column precision in the Hive table is `decimal(19,6)`.
> - The model measure precision is `decimal(29,6)`.
> - When querying, the result will be `null`.
> In the Spark event log for the query, the `cast` precision is
> `decimal(19,6)`. Directly retrieving data from the Parquet file yields the
> following:
> - When the `cast` precision is `DECIMAL(19,6)`, the result is `null`.
> - When the `cast` precision is `DECIMAL(29,6)`, the result is correct.
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