[PR] [SQL][SPARK-51113] Fix correctness with UNION/EXCEPT/INTERSECT inside a view [spark]

[via GitHub]

vladimirg-db opened a new pull request, #49835:
URL: https://github.com/apache/spark/pull/49835

   ### What changes were proposed in this pull request?
   
   Fix correctness with UNION/EXCEPT/INTERSECT inside a view.
   
   In the following examples the SQL Parser considers UNION/EXCEPT/INTERSECT 
keywords as aliases and drops the rest of the query:
   
   ```
   spark.sql("CREATE OR REPLACE VIEW v1 AS SELECT 1 AS col1 UNION SELECT 2 
UNION SELECT 3 UNION SELECT 4")
   spark.sql("SELECT * FROM v1").show()
   spark.sql("SELECT * FROM v1").queryExecution.analyzed
   
   spark.sql("CREATE OR REPLACE VIEW v1 AS SELECT 1 AS col1 EXCEPT SELECT 2 
EXCEPT SELECT 1 EXCEPT SELECT 2")
   spark.sql("SELECT * FROM v1").show()
   spark.sql("SELECT * FROM v1").queryExecution.analyzed
   
   spark.sql("CREATE OR REPLACE VIEW t1 AS SELECT 1 AS col1 INTERSECT SELECT 1 
INTERSECT SELECT 2 INTERSECT SELECT 2")
   spark.sql("SELECT * FROM v1").show()
   spark.sql("SELECT * FROM v1").queryExecution.analyzed
   ```
   
   
![image](https://github.com/user-attachments/assets/ef726178-2375-4ebc-a7e3-88f1991d1016)
   
![image](https://github.com/user-attachments/assets/50b4b7ba-bc7d-4fc1-a921-f4cbfcab79a3)
   
![image](https://github.com/user-attachments/assets/85b65325-5dd9-4d74-b46d-8ea203ce1039)
   
   There's no correctness issue associated with regular queries (without the 
view). Apparently that's because we use `ParserInterface.parsePlan` 
(`singleStatement` term in Spark SQL grammar) for [regular 
queries](https://github.com/apache/spark/blob/b968ce1d3ac1b72019b30bf3d4e11d9574ba1205/sql/core/src/main/scala/org/apache/spark/sql/classic/SparkSession.scala#L490)
 and `ParserInterface.parseQuery` (`query` term in Spark SQL grammar) for [view 
bodies](https://github.com/apache/spark/blob/b968ce1d3ac1b72019b30bf3d4e11d9574ba1205/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/catalog/SessionCatalog.scala#L986).
 The difference is that `singleStatement` [ends in 
EOF](https://github.com/apache/spark/blob/b968ce1d3ac1b72019b30bf3d4e11d9574ba1205/sql/api/src/main/antlr4/org/apache/spark/sql/catalyst/parser/SqlBaseParser.g4#L144).
   
   ### Why are the changes needed?
   
   Correctness issue fix.
   
   ### Does this PR introduce _any_ user-facing change?
   
   Yes, the results of queries on top of aforementioned views are gonna be 
correct.
   
   ### How was this patch tested?
   
   New `view-correctness` suite.
   
   ### Was this patch authored or co-authored using generative AI tooling?
   
   No.


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