[jira] [Updated] (TAJO-619) SELECT count(1) after joins on text keys causes wrong plans

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

     [ https://issues.apache.org/jira/browse/TAJO-619?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Hyunsik Choi updated TAJO-619:
------------------------------

    Attachment: TAJO-619.patch

> SELECT count(1) after joins on text keys causes wrong plans
> -----------------------------------------------------------
>
>                 Key: TAJO-619
>                 URL: https://issues.apache.org/jira/browse/TAJO-619
>             Project: Tajo
>          Issue Type: Bug
>          Components: planner/optimizer
>            Reporter: Hyunsik Choi
>            Assignee: Hyunsik Choi
>            Priority: Minor
>             Fix For: 0.8-incubating
>
>         Attachments: TAJO-619.patch
>
>
> {code}
> select count(1) from table1 join table2 on table1.name = table2.name;
> {code}
> When there are constant values in select list and equi-join keys are text columns, it causes some errors due to schema mismatch.
> Its cause of this bug is as follows:
>  * the number 1 results in a generated column name '?literal'. 
>  * This name is used in both table1 and table2. Output schemas of table1 and table2 include ?literal
>  * The input schema of join has only three columns because ?literal is duplicated name.
> So, its essential bug may be one of following:
>  * The constant value is evaluated twice. In other words, literal? occurs in both table1 and table2.
>  * Schema class does not allow the same column name.



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