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https://issues.apache.org/jira/browse/HIVE-24976?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Krisztian Kasa reassigned HIVE-24976:
-------------------------------------
Assignee: Krisztian Kasa
> CBO: count(distinct) in a window function fails CBO
> ---------------------------------------------------
>
> Key: HIVE-24976
> URL: https://issues.apache.org/jira/browse/HIVE-24976
> Project: Hive
> Issue Type: Bug
> Components: CBO
> Reporter: Gopal Vijayaraghavan
> Assignee: Krisztian Kasa
> Priority: Major
>
> {code}
> create temporary table tmp_tbl(
> `rule_id` string,
> `severity` string,
> `alert_id` string,
> `alert_type` string);
> explain cbo
> select `k`.`rule_id`,
> count(distinct `k`.`alert_id`) over(partition by `k`.`rule_id`) `subj_cnt`
> from tmp_tbl k
> ;
> explain
> select `k`.`rule_id`,
> count(distinct `k`.`alert_id`) over(partition by `k`.`rule_id`) `subj_cnt`
> from tmp_tbl k
> ;
> {code}
> Fails CBO, because the count(distinct) is not being recognized as belonging
> to a windowing operation.
> So it throws the following exception
> {code}
> throw new CalciteSemanticException("Distinct without an
> aggregation.",
> UnsupportedFeature.Distinct_without_an_aggreggation);
> {code}
> https://github.com/apache/hive/blob/73c3770d858b063c69dea6c64a759f8fdacad460/ql/src/java/org/apache/hadoop/hive/ql/parse/CalcitePlanner.java#L4914
> This prevents a query like this from using a materialized view which already
> exists in the system (the MV obviously does not contain this expression, but
> represents a complex transform from a JSON structure into a columnar layout).
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