[jira] [Commented] (KYLIN-2841) LIMIT is buggy with subquery

["zhengdong (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KYLIN-2841?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16155126#comment-16155126 ] 

zhengdong commented on KYLIN-2841:
----------------------------------

I encountered this recently, seems a bug of query engine.

> LIMIT is buggy with subquery
> ----------------------------
>
>                 Key: KYLIN-2841
>                 URL: https://issues.apache.org/jira/browse/KYLIN-2841
>             Project: Kylin
>          Issue Type: Bug
>    Affects Versions: v2.1.0
>            Reporter: Mu Kong
>
> Hi, all.
> I found that limit in the web UI seems not behaving as expected.
> When I run a query like the follows:
> {code:sql}
> SELECT
>   SUM(col3) AS col4, 
>   SUM(col5) AS total_col5,
>   col1 
> FROM
> (
>   SELECT
>     col1,
>     col2,
>     MAX(col3) AS col3,
>     COUNT(*) AS col5
>   FROM db.table
>   WHERE col6 = 'somestring'
>   GROUP BY col1, col2
> )
> GROUP BY col1
> {code}
> When I specify the limit as 50, the result has 19 records, and when I specify the limit as 500000, there are 90+ records in the result and each record has higher col4 and total_col5.
> But for query that doesn't have subquery, the result remains the same no matter how I change the limit.
> I guess for the query with subquery, limit somehow limits the number of the result from the inner query instead of the result of the outer query.



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