[jira] [Updated] (DRILL-6146) UNION with empty input on any one side returns incorrect results

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

     [ https://issues.apache.org/jira/browse/DRILL-6146?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Khurram Faraaz updated DRILL-6146:
----------------------------------
    Priority: Critical  (was: Major)

> UNION with empty input on any one side returns incorrect results
> ----------------------------------------------------------------
>
>                 Key: DRILL-6146
>                 URL: https://issues.apache.org/jira/browse/DRILL-6146
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Query Planning & Optimization
>    Affects Versions: 1.12.0
>            Reporter: Khurram Faraaz
>            Assignee: Vitalii Diravka
>            Priority: Critical
>
> When any one side of the UNION has an empty file as input, Drill returns incorrect results.
>  
> table t3 does not have any data inserted into its rows. Postgress returns 1 as the result for both the queries, whereas Drill does not.
>  
> {noformat}
> postgres=# create table t3(id int, name varchar(25));
> CREATE TABLE 
> postgres=# select * from (values(1)) t union select id from t3;
>        1
>  
> postgres=# select id from t3 union select * from (values(1)) t;
>   1
>  {noformat}
>  
>  
> Results from Drill 1.12.0-mapr, note we return result 1 as result after the union.
> We have a directory named empty_JSON_f , and it has a single empty JSON file (that JSON file has no content in it, it is empty).
>  
> {noformat}
> 0: jdbc:drill:schema=dfs.tmp> select * from (values(1)) UNION select id from empty_JSON_f;
> +---------+
> | EXPR$0  |
> +---------+
> | 1       |
> +---------+
> 1 row selected (2.272 seconds){noformat}
> However, in this query we return null and loose the value 1 from the right hand side, after the union, this doesn't seem correct 
> {noformat}
> 0: jdbc:drill:schema=dfs.tmp> select id from empty_JSON_f UNION select * from (values(1));
> +-------+
> |  id   |
> +-------+
> | null  |
> +-------+
> 1 row selected (0.33 seconds){noformat}
>  



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