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https://issues.apache.org/jira/browse/CALCITE-6516?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17871771#comment-17871771
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Julian Hyde commented on CALCITE-6516:
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[~lchistov1987], Thanks for coming up with a test case. It helps make the
discussion more concrete.
I believe there are existing jira cases requesting that we use more bits for
the "accumulator" of AVG and STDEV aggregate functions than the final result.
If the final step is a division by a positive integer, and therefore loses some
bits, clearly those extra bits are sometimes required. Can you look up those
cases? Maybe this is a duplicate of one of those.
> AVG to SUM+COUNT transformation inserts invalid CAST call
> ---------------------------------------------------------
>
> Key: CALCITE-6516
> URL: https://issues.apache.org/jira/browse/CALCITE-6516
> Project: Calcite
> Issue Type: Bug
> Affects Versions: 1.37.0
> Reporter: Leonid Chistov
> Priority: Major
>
> As described in https://issues.apache.org/jira/browse/CALCITE-4911.
> In Calcite:
> {code:java}
> select avg(comm) as a from "scott".emp{code}
> This SQL physical plan is:
> {noformat}
> EnumerableCalc(expr#0..1=[{inputs}], expr#2=[0], expr#3=[=($t1, $t2)],
> expr#4=[null:DECIMAL(19, 2)], expr#5=[CASE($t3, $t4, $t0)],
> expr#6=[CAST($t5):DECIMAL(7, 2)], expr#7=[/($t6, $t1)],
> expr#8=[CAST($t7):DECIMAL(7, 2)], A=[$t8])
> EnumerableAggregate(group=[{}], agg#0=[$SUM0($6)], agg#1=[COUNT($6)])
> EnumerableTableScan(table=[[scott, EMP]]){noformat}
> Problem here is that cast of SUM result to DECIMAL(7, 2) is not correct and
> may cause overflow error at runtime or result in not expected data truncation.
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