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
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) . 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.