Zoltan Haindrich created HIVE-23364:
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Summary: Push down null-safe cast-s
Key: HIVE-23364
URL: https://issues.apache.org/jira/browse/HIVE-23364
Project: Hive
Issue Type: Improvement
Reporter: Zoltan Haindrich
right now we may endup with conditionals like this:
{code}
predicate: CASE WHEN (_col1 is not null) THEN (CASE WHEN
(_col4 is not null) THEN ((CAST( _col4 AS STRING) = CAST( _col1 AS STRING)))
ELSE (('EMPTY' = CAST( _col1 AS STRING))) END) ELSE (CASE WHEN (_col4 is not
null) THEN ((CAST( _col4 AS STRING) = 'EMPTY')) ELSE (('EMPTY' = 'EMPTY')) END)
END (type: boolean)
{code}
if this is after a join operator; then the same CAST might be evaluated for the
same value...
in case the CAST is to a type which doesn't widen nullabiltity in Hive - we may
push down the CAST
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