Zhenhua Wang created SPARK-20104:
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Summary: Don't estimate IsNull or IsNotNull predicates for
non-leaf node
Key: SPARK-20104
URL: https://issues.apache.org/jira/browse/SPARK-20104
Project: Spark
Issue Type: Bug
Components: SQL
Affects Versions: 2.2.0
Reporter: Zhenhua Wang
In current stage, we don't have advanced statistics such as sketches or
histograms. As a result, some operator can't estimate `nullCount` accurately.
E.g. left outer join estimation does not accurately update `nullCount`
currently. So for IsNull and IsNotNull predicates, we only estimate them when
the child is a leaf node, whose `nullCount` is accurate.
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