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https://issues.apache.org/jira/browse/DRILL-5691?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16244567#comment-16244567
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ASF GitHub Bot commented on DRILL-5691:
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Github user amansinha100 commented on the issue:
https://github.com/apache/drill/pull/889
@weijietong I ran the functional tests with the PR and saw some failures.
While debugging those failures, I found the simple scalar aggregate case works
but anything with compound aggregate expressions throws a CannotPlanException,
for example:
explain plan for select count(*) from cp.`tpch/lineitem.parquet` l where
l_quantity < (select max(l2.l_quantity) + 1 from cp.`tpch/lineitem.parquet` l2)
Here, the right side of the inequality join is actually a scalar but the
JoinUtils.isScalar() method does not detect it correctly. The reason is the
right side is a DrillProjectRel whose input is a RelSubSet. The RelSubSet has
a DrillAggregateRel but it looks like currently Calcite does not detect this is
a scalar aggregate if it occurs as part of a RelSubSet. I see Calcite has a
comment in [1] which points to an open JIRA CALCITE-1048.
[1]
https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/rel/metadata/RelMdMaxRowCount.java#L165
> multiple count distinct query planning error at physical phase
> ---------------------------------------------------------------
>
> Key: DRILL-5691
> URL: https://issues.apache.org/jira/browse/DRILL-5691
> Project: Apache Drill
> Issue Type: Bug
> Components: Execution - Relational Operators
> Affects Versions: 1.9.0, 1.10.0
> Reporter: weijie.tong
>
> I materialized the count distinct query result in a cache , added a plugin
> rule to translate the (Aggregate、Aggregate、Project、Scan) or
> (Aggregate、Aggregate、Scan) to (Project、Scan) at the PARTITION_PRUNING phase.
> Then ,once user issue count distinct queries , it will be translated to query
> the cache to get the result.
> eg1: " select count(*),sum(a) ,count(distinct b) from t where dt=xx "
> eg2:"select count(*),sum(a) ,count(distinct b) ,count(distinct c) from t
> where dt=xxx "
> eg3:"select count(distinct b), count(distinct c) from t where dt=xxx"
> eg1 will be right and have a query result as I expected , but eg2 will be
> wrong at the physical phase.The error info is here:
> https://gist.github.com/weijietong/1b8ed12db9490bf006e8b3fe0ee52269.
> eg3 will also get the similar error.
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