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https://issues.apache.org/jira/browse/IMPALA-8205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17105911#comment-17105911
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ASF subversion and git services commented on IMPALA-8205:
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Commit a93f2c2675d72d03a6e8430126f3f461b153ca26 in impala's branch
refs/heads/master from Chang Wu
[ https://gitbox.apache.org/repos/asf?p=impala.git;h=a93f2c2 ]
IMPALA-8205: Support number of true and false statistics for boolean column
This change compute the real number of true and false statistics
information for boolean columns. Before this, impala used to set
numTrues and numFalses to hardcoded -1 to indicate that its
statistics is missing.
Test Done:
Append the numTrue and numFalse test for all the statistics-related
test cases including the non-incremental, incremental and other test
cases.
Change-Id: I991bee8e7fdc644d908289f5fe2ee8032cc2c431
Reviewed-on: http://gerrit.cloudera.org:8080/14666
Reviewed-by: Impala Public Jenkins <[email protected]>
Tested-by: Impala Public Jenkins <[email protected]>
> 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
> Assignee: wuchang
> Priority: Major
> Labels: impala, numFalse, numTrue, statistics
>
> 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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