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Posted to issues@impala.apache.org by "wuchang (JIRA)" <ji...@apache.org> on 2019/02/15 09:44:00 UTC

[jira] [Created] (IMPALA-8205) Illegal statistics for numFalse and numTrue

wuchang created IMPALA-8205:
-------------------------------

             Summary: Illegal statistics for numFalse and numTrue
                 Key: IMPALA-8205
                 URL: https://issues.apache.org/jira/browse/IMPALA-8205
             Project: IMPALA
          Issue Type: Bug
            Reporter: wuchang


When impala compute statistics, it set *numFalse = -1* and *numTrue = 1* when the statistic is missing;

*-1* for *numFalse* will corrupt some query engine like Presto and there already exists some PR report and hotfix it : [presto-11859|https://github.com/prestodb/presto/pull/11859]

*1* for *numTrue* is also unreasonable because we are not sure whether it indicates the real numTrue statistics or a missing statistics;

Also, previously , the *nullCount* also use -1 to indicate its absence which also caused problem for Presto. Presto has to add a hotfix for it([presto-11549|https://github.com/prestodb/presto/pull/11549]) . But it is a fortunate that impala has fixed this bug;

It is necessary to set to null when these statistics are absent instead of -1 and 1.



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