Peter Toth 24be81689c [SPARK-32241][SQL] Remove empty children of union ... ### What changes were proposed in this pull request? This PR removes the empty child relations of a `Union`. E.g. the query `SELECT c FROM t UNION ALL SELECT c FROM t WHERE false` has the following plan before this PR: ``` == Physical Plan == Union :- *(1) Project [value#219 AS c#222] : +- *(1) LocalTableScan [value#219] +- LocalTableScan <empty>, [c#224] ``` and after this PR: ``` == Physical Plan == *(1) Project [value#219 AS c#222] +- *(1) LocalTableScan [value#219] ``` ### Why are the changes needed? To have a simpler plan. ### Does this PR introduce _any_ user-facing change? No. ### How was this patch tested? Added new UTs. Closes #29053 from peter-toth/SPARK-32241-remove-empty-children-of-union. Authored-by: Peter Toth <peter.toth@gmail.com> Signed-off-by: Wenchen Fan <wenchen@databricks.com>		2020-07-14 04:26:29 +00:00
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benchmarks	[SPARK-30413][SQL] Avoid WrappedArray roundtrip in GenericArrayData constructor, plus related optimization in ParquetMapConverter	2020-01-19 19:12:19 -08:00
src	[SPARK-32241][SQL] Remove empty children of union	2020-07-14 04:26:29 +00:00
pom.xml	[SPARK-30950][BUILD] Setting version to 3.1.0-SNAPSHOT	2020-02-25 19:44:31 -08:00