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Posted to issues@trafodion.apache.org by "Qifan Chen (JIRA)" <ji...@apache.org> on 2015/10/23 19:34:27 UTC

[jira] [Created] (TRAFODION-1555) The existing heuristic to not consider MDAM scan is too harsh

Qifan Chen created TRAFODION-1555:
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             Summary: The existing heuristic to not consider MDAM scan is too harsh
                 Key: TRAFODION-1555
                 URL: https://issues.apache.org/jira/browse/TRAFODION-1555
             Project: Apache Trafodion
          Issue Type: Bug
          Components: sql-cmp
            Reporter: Qifan Chen
             Fix For: 2.0-incubating


The heuristic that the majority of the key columns should have key predicates does not consider the UECs associated with each key column.  The heuristic may hurt scan performance when these UECs are very low. 



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