WangGuangxin opened a new pull request, #36873:
URL: https://github.com/apache/spark/pull/36873
### What changes were proposed in this pull request?
Cast from Integer to Float or from Long to Double/Float may loss precision
if the length of Integer/Long beyonds the **significant digits** of a
Double(which is 15 or 16 digits) or Float(which is 7 or 8 digits).
For example, ```select *, cast(a as int) from (select cast(33554435 as foat)
a )``` gives `33554436` instead of `33554435`.
When it comes the optimization rule `UnwrapCastInBinaryComparison`, it may
result in incorrect (confused) result .
We can reproduce it with following script.
```
spark.range(10).map(i => 64707595868612313L).createOrReplaceTempView("tbl")
val df = sql("select * from tbl where cast(value as double) =
cast('64707595868612313' as double)")
df.explain(true)
df.show()
```
With we disable this optimization rule , it returns 10 records.
But if we enable this optimization rule, it returns empty, since the sql is
optimized to
```
select * from tbl where value = 64707595868612312L
```
### Why are the changes needed?
Fix the behavior that may confuse users (or maybe a bug?)
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
Add a new UT
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