[jira] [Updated] (KYLIN-4061) Swap inner join's left side, right side table will get different result when query

["weibin0516 (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/KYLIN-4061?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

weibin0516 updated KYLIN-4061:
------------------------------
    Attachment: succeed.png
                failed.png

> Swap inner join's left side, right side table will get different result when query
> ----------------------------------------------------------------------------------
>
>                 Key: KYLIN-4061
>                 URL: https://issues.apache.org/jira/browse/KYLIN-4061
>             Project: Kylin
>          Issue Type: Bug
>          Components: Query Engine
>    Affects Versions: v2.5.2
>            Reporter: weibin0516
>            Priority: Major
>         Attachments: failed.png, succeed.png
>
>
> When the left side table of inner join is a fact table and the right side table is a lookup table, will query cube and get correct result. Sql is as follows.
> ```
> SELECT KYLIN_SALES.TRANS_ID, SUM(KYLIN_SALES.PRICE), COUNT(KYLIN_ACCOUNT.ACCOUNT_ID)
> FROM KYLIN_SALES
> INNER JOIN KYLIN_ACCOUNT ON KYLIN_SALES.BUYER_ID = KYLIN_ACCOUNT.ACCOUNT_ID
> WHERE KYLIN_SALES.LSTG_SITE_ID != 1000
> GROUP BY KYLIN_SALES.TRANS_ID
> ORDER BY TRANS_ID
> LIMIT 10;
> ```
>  
> However，when swap the left and right side tables of the inner join will failed due to no realization found. Sql is as follows.
> ```
> SELECT KYLIN_SALES.TRANS_ID, SUM(KYLIN_SALES.PRICE), COUNT(KYLIN_ACCOUNT.ACCOUNT_ID)
> FROM KYLIN_ACCOUNT
> INNER JOIN KYLIN_SALES ON KYLIN_SALES.BUYER_ID = KYLIN_ACCOUNT.ACCOUNT_ID
> WHERE KYLIN_SALES.LSTG_SITE_ID != 1000
> GROUP BY KYLIN_SALES.TRANS_ID
> ORDER BY TRANS_ID
> LIMIT 10;
> ```
> We know that the above two sql semantics are consistent and should return the same result. 
> I looked at the source code, kylin will use context.firstTableScan(assigned in OLAPTableScan.implementOLAP) as the fact table, whether it is or not.
> Is this a bug, do we need to fix it?



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