[GitHub] [hudi] dongkelun commented on a change in pull request #3517: [HUDI-2343]Fix the exception for mergeInto when the primaryKey and preCombineField of source table and target table differ in case only

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

dongkelun commented on a change in pull request #3517:
URL: https://github.com/apache/hudi/pull/3517#discussion_r713041105



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File path: hudi-spark-datasource/hudi-spark/src/main/scala/org/apache/spark/sql/hudi/command/MergeIntoHoodieTableCommand.scala
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@@ -196,9 +196,11 @@ case class MergeIntoHoodieTableCommand(mergeInto: MergeIntoTable) extends Runnab
   }
 
   private def isEqualToTarget(targetColumnName: String, sourceExpression: Expression): Boolean = {
+    val sourceColNameMap = sourceDFOutput.map(attr => (attr.name.toLowerCase, attr.name)).toMap
+
     sourceExpression match {
-      case attr: AttributeReference if attr.name.equalsIgnoreCase(targetColumnName) => true
-      case Cast(attr: AttributeReference, _, _) if attr.name.equalsIgnoreCase(targetColumnName) => true
+      case attr: AttributeReference if sourceColNameMap(attr.name.toLowerCase).equals(targetColumnName) => true

Review comment:
       Hi,is it like this?
   ```scala
   val resolver = sparkSession.sessionState.conf.resolver
   case attr: AttributeReference if resolver(attr.name, targetColumnName) => true
   ```
   I'm not sure if I understand,resolver is not case sensitive when comparing equality.However, the comparison of equality here must be case sensitive.Therefore, use sourceColNameMap(attr.name.toLowerCase) to obtain the original column name of source table without case conversion,Then compare with targetcolumnname for equality.If not, add the corresponding column name with withcolumn later. It is case sensitive because sourceDF is case sensitive when writing data.




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