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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