[GitHub] [spark] viirya commented on a change in pull request #27991: [SPARK-31227][SQL] Non-nullable null type in complex types should not coerce to nullable type

[GitBox <gi...@apache.org>]

viirya commented on a change in pull request #27991: [SPARK-31227][SQL] Non-nullable null type in complex types should not coerce to nullable type
URL: https://github.com/apache/spark/pull/27991#discussion_r396917172
 
 

 ##########
 File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Cast.scala
 ##########
 @@ -210,8 +206,15 @@ object Cast {
     case _ => false  // overflow
   }
 
+  /**
+   * Returns `true` iff it should change the nullability of this type in map type,
+   * array type, expressions such as cast, etc.
+   *
+   * Note that you should take the nullability context into account.
+   * For example, it should not force to nullable type when null type in array
+   * type is non-nullable which means an empty array of null type.
+   */
 
 Review comment:
   But we use it like:
   
   ```
   abstract class CastBase ... {
     override def nullable: Boolean = Cast.forceNullable(child.dataType, dataType) || child.nullable
     ...
   }
   ```
   
   Will we change `nullable` for something based on `CastBase`? 

----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
 
For queries about this service, please contact Infrastructure at:
users@infra.apache.org


With regards,
Apache Git Services

---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscribe@spark.apache.org
For additional commands, e-mail: reviews-help@spark.apache.org