[jira] [Created] (TRAFODION-2575) UPDATE STATS sometimes fails on very long varchars

["David Wayne Birdsall (JIRA)" <ji...@apache.org>]

David Wayne Birdsall created TRAFODION-2575:
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             Summary: UPDATE STATS sometimes fails on very long varchars
                 Key: TRAFODION-2575
                 URL: https://issues.apache.org/jira/browse/TRAFODION-2575
             Project: Apache Trafodion
          Issue Type: Bug
          Components: sql-cmp
    Affects Versions: 2.2-incubating
            Reporter: David Wayne Birdsall
            Assignee: David Wayne Birdsall


One symptom is observing 6003 or 6004 warnings after UPDATE STATISTICS is done. That is, UPDATE STATISTICS seems to succeed, but when repeated it fails with an error 9200, and 6003 or 6004 warnings. These warnings indicate that the histogram interval values are not in order. In one example that I debugged, the problem was that we used a SELECT statement to compute aggregates on the column, and the plan for that SELECT statement did not sort the results, even though an ORDER BY was specified. While debugging that, I ran into several other issues with sorts on long varchars. Concluding that the engine is simply not up to prime-time for such sorts (and seeing that such sorts are unneeded anyway), I plan to change UPDATE STATISTICS to first truncate the string to a shorter length and then generate the SELECT.



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