[teiid-issues] [JBoss JIRA] (TEIID-2725) Group by doesn't work with MongoDB

[Ivan Chan (JIRA)]

Ivan Chan created TEIID-2725:
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             Summary: Group by doesn't work with MongoDB
                 Key: TEIID-2725
                 URL: https://issues.jboss.org/browse/TEIID-2725
             Project: Teiid
          Issue Type: Bug
          Components: Query Engine
    Affects Versions: 8.6
         Environment: Teiid with MongoDB
            Reporter: Ivan Chan
            Assignee: Steven Hawkins


Group by SQL with/ without aggregate function returns incorrect values:

For example:

Original SQL:

select "grade", sum("score") as "sum_score" from "mongoDBDS"."grades" group by "grade" order by "grade"

 

Transform query:

SELECT grades.grade AS c_0, SUM(grades.score) AS c_1 FROM grades GROUP BY grades.grade ORDER BY c_0

$group:{ "_id" : "$grade" , "c_1" : { "$sum" : "$score"}}

$project:{ "c_0" : "$grade" , "c_1" : 1}

$sort:{ "c_0" : 1}

Expected Result:
grade   score
A	187
F	55

Actual Result:  (INCORRECT)
grade	score
	242

It only returns SUM(score) and group by fields are ignore. 

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