## What changes were proposed in this pull request?
If table is renamed to a existing new location, data won't show up.
```
scala> Seq("hello").toDF("a").write.format("parquet").saveAsTable("t")
scala> sql("select * from t").show()
+-----+
| a|
+-----+
|hello|
+-----+
scala> sql("alter table t rename to test")
res2: org.apache.spark.sql.DataFrame = []
scala> sql("select * from test").show()
+---+
| a|
+---+
+---+
```
The file layout is like
```
$ tree test
test
├── gabage
└── t
├── _SUCCESS
└── part-00000-856b0f10-08f1-42d6-9eb3-7719261f3d5e-c000.snappy.parquet
```
In Hive, if the new location exists, the renaming will fail even the location is empty.
We should have the same validation in Catalog, in case of unexpected bugs.
## How was this patch tested?
New unit test.
Author: Gengliang Wang <gengliang.wang@databricks.com>
Closes#21655 from gengliangwang/validate_rename_table.
33952cfa81