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Posted to issues@impala.apache.org by "Peter Ebert (JIRA)" <ji...@apache.org> on 2018/09/07 19:09:00 UTC

[jira] [Created] (IMPALA-7547) For distinct queries use dictionary encoded page instead of reading all data

Peter Ebert created IMPALA-7547:
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             Summary: For distinct queries use dictionary encoded page instead of reading all data
                 Key: IMPALA-7547
                 URL: https://issues.apache.org/jira/browse/IMPALA-7547
             Project: IMPALA
          Issue Type: Improvement
            Reporter: Peter Ebert


When dictionary encoding is in use the lookup table should contain a distinct list of all values in the data, can skip reading the values and just read the header to get distinct values.

 

Realize this would be a big change to the read/scanner threads but could greatly speed up distinct queries.



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