Github user jaceklaskowski commented on a diff in the pull request:
https://github.com/apache/spark/pull/19773#discussion_r151739604
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/command/ddl.scala ---
@@ -318,16 +318,28 @@ case class AlterTableChangeColumnCommand(
s"'${newColumn.name}' with type '${newColumn.dataType}'")
}
+ val changeSchema = originColumn.dataType != newColumn.dataType
val newSchema = table.schema.fields.map { field =>
if (field.name == originColumn.name) {
- // Create a new column from the origin column with the new comment.
- addComment(field, newColumn.getComment)
+ var newField = field
--- End diff --
I'd recommend getting rid of this `var` and re-writting the code as follows:
```
val newField = newColumn.getComment.map(...).getOrElse(field)
```
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