[jira] [Commented] (DRILL-5130) UNION ALL difference in results

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

    [ https://issues.apache.org/jira/browse/DRILL-5130?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16050618#comment-16050618 ] 

Arina Ielchiieva commented on DRILL-5130:
-----------------------------------------

The problem is with incorrectly overridden explainTerms method. This method is responsible for describing the inputs and attributes of the relational expression.
In DrillValuesRel this method was incorrectly overriden, in ValuesPrel is was not overriden at all. Thus two Values nodes with the same row type and row count were considered to be the same, though their values were different. During planning Calcite removed discarded duplicated DrillValuesRel and ValuesPrel (duplicates are found by comparing string representation of two relational expressions to generate such representation explainTerms is used) and used the same one for both Values expressions.

Query:
{noformat}
values('a') union all values('b')
{noformat}

Plan:
{noformat}
00-00    Screen
00-01      Project(EXPR$0=[$0])
00-02        UnionAll(all=[true])
00-04          Values
00-03          Values
{noformat}

> UNION ALL difference in results
> -------------------------------
>
>                 Key: DRILL-5130
>                 URL: https://issues.apache.org/jira/browse/DRILL-5130
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Execution - Flow, Query Planning & Optimization
>    Affects Versions: 1.9.0
>            Reporter: Khurram Faraaz
>            Assignee: Arina Ielchiieva
>
> Drill 1.9.0 git commit ID: 51246693
> {noformat}
> 0: jdbc:drill:schema=dfs.tmp> values(1,2,3,4,5,6) union all values(7,8,9,10,11,12);
> +---------+---------+---------+---------+---------+---------+
> | EXPR$0  | EXPR$1  | EXPR$2  | EXPR$3  | EXPR$4  | EXPR$5  |
> +---------+---------+---------+---------+---------+---------+
> | 7       | 8       | 9       | 10      | 11      | 12      |
> | 7       | 8       | 9       | 10      | 11      | 12      |
> +---------+---------+---------+---------+---------+---------+
> 2 rows selected (0.209 seconds)
> {noformat}
> Postgres 9.3
> {noformat}
> postgres=# values(1,2,3,4,5,6) union all values(7,8,9,10,11,12);
>  column1 | column2 | column3 | column4 | column5 | column6 
> ---------+---------+---------+---------+---------+---------
>        1 |       2 |       3 |       4 |       5 |       6
>        7 |       8 |       9 |      10 |      11 |      12
> (2 rows)
> {noformat}



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