[teiid-issues] [JBoss JIRA] (TEIID-3743) Multiple Count Distinct Columns Fails for Impala

[Scott Wallace (JIRA)]

Scott Wallace created TEIID-3743:
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             Summary: Multiple Count Distinct Columns Fails for Impala
                 Key: TEIID-3743
                 URL: https://issues.jboss.org/browse/TEIID-3743
             Project: Teiid
          Issue Type: Feature Request
          Components: Misc. Connectors
    Affects Versions: 8.11.4
            Reporter: Scott Wallace
            Assignee: Steven Hawkins


Teiid Impala translator incorrectly allows multiple count distinct columns.

Per Cloudera documentation:
{quote}By default, Impala only allows a single COUNT(DISTINCT columns) expression in each query.

To produce the same result as multiple COUNT(DISTINCT) expressions, you can use the following technique for queries involving a single table:

select v1.c1 result1, v2.c1 result2 from (select count(distinct col1) as c1 from t1) v1 cross join (select count(distinct col2) as c1 from t1) v2;{quote}

The Teiid-Impala translator should ideally rewrite the query as necessary so that the query does not fail executing multiple count distincts against Impala.



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