wangyum opened a new pull request #34580:
URL: https://github.com/apache/spark/pull/34580
### What changes were proposed in this pull request?
This pr fix push foldable into CaseWhen branches if elseValue is empty. For
example:
```scala
spark.sql("CREATE TABLE t1(bool boolean, number int) using parquet")
spark.sql("INSERT INTO t1 VALUES(false, 1)")
spark.sql(
"""
|SELECT *
|FROM (SELECT *,
| CASE
| WHEN bool THEN 'I am not null'
| END AS conditions
| FROM t1) t
|WHERE conditions IS NULL
|""".stripMargin).show
}
```
How do we optimize the filter conditions before this pr:
```
Filter isnull(CASE WHEN bool#7 THEN I am not null END) -> Filter CASE WHEN
bool#7 THEN isnull(I am not null) END -> Filter (bool#7 AND isnull(I am not
null)) -> Filter (bool#7 AND false)
```
How do we optimize the filter conditions after this pr:
```
Filter isnull(CASE WHEN bool#7 THEN I am not null END) -> Filter CASE WHEN
bool#7 THEN isnull(I am not null) ELSE isnull(null) END -> Filter CASE WHEN
bool#7 THEN false ELSE isnull(null) END -> Filter CASE WHEN bool#7 THEN false
ELSE true END -> Filter NOT (bool#7 <=> true)
```
### Why are the changes needed?
Fix correctness issue.
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
Unit test.
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