[jira] [Commented] (DRILL-2002) Confusing "star" behavior in UNION ALL operator

["Sean Hsuan-Yi Chu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DRILL-2002?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14355266#comment-14355266 ] 

Sean Hsuan-Yi Chu commented on DRILL-2002:
------------------------------------------

Union-All on SELECT * (wildcard symbol) is supported only for the cases where schema (i.e., hive, view) is available. If * is applied on schema-less data source, exception will be thrown (see DRILL-2414).

For design specification document, please refer to DRILL-2207

> Confusing "star" behavior in UNION ALL operator
> -----------------------------------------------
>
>                 Key: DRILL-2002
>                 URL: https://issues.apache.org/jira/browse/DRILL-2002
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Query Planning & Optimization
>    Affects Versions: 0.8.0
>            Reporter: Victoria Markman
>            Assignee: Sean Hsuan-Yi Chu
>             Fix For: 0.9.0
>
>
> t1.json
> {code}
> { "a1": 1 ,    "b1" : 1}
> { "a1": 2 ,    "b1" : 1}
> { "a1": 2 ,    "b1" : 2}
> { "a1": 3 ,    "b1" : 2}
> { "a1": null , "b1" : 3}
> {code}
> Star in both legs of UNION ALL works:
> {code}
> 0: jdbc:drill:schema=dfs> select * from `t1.json` union all select * from `t1.json`;
> +------------+------------+
> |     a1     |     b1     |
> +------------+------------+
> | 1          | 1          |
> | 2          | 1          |
> | 2          | 2          |
> | 3          | 2          |
> | null       | 3          |
> | 1          | 1          |
> | 2          | 1          |
> | 2          | 2          |
> | 3          | 2          |
> | null       | 3          |
> +------------+------------+
> 10 rows selected (0.126 seconds)
> {code}
> I expected this to work in structured, but it seems that since planner has no idea about meta data, error message seems reasonable:
> {code}
> 0: jdbc:drill:schema=dfs> select a1, b1 from `t1.json` union all select * from `t1.json`;
> Query failed: Query failed: Failure validating SQL. org.eigenbase.util.EigenbaseContextException: At line 1, column 47: Column count mismatch in UNION ALL
> Error: exception while executing query: Failure while executing query. (state=,code=0)
> {code}
> Query below returns very confusing result. I expected it to error out like the query above:
> {code}
> 0: jdbc:drill:schema=dfs> select a1 from `t1.json` union all select * from `t1.json`;
> +------------+
> |     a1     |
> +------------+
> | 1          |
> | 2          |
> | 2          |
> | 3          |
> | null       |
> | 1          |
> | 2          |
> | 2          |
> | 3          |
> | null       |
> +------------+
> 10 rows selected (0.111 seconds)
> {code}



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