[GitHub] [flink] twalthr commented on a diff in pull request #19490: [FLINK-27263][table] Rename the metadata column to the user specified…

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

twalthr commented on code in PR #19490:
URL: https://github.com/apache/flink/pull/19490#discussion_r852601520


##########
flink-table/flink-table-planner/src/test/java/org/apache/flink/table/planner/operations/MergeTableLikeUtilTest.java:
##########
@@ -431,6 +433,100 @@ public void mergeOverwritingMetadataColumnsDuplicate() {
         assertThat(mergedSchema, equalTo(expectedSchema));
     }
 
+    @Test
+    public void mergeIncludingMetadataColumnWithSameMetadataKey() {
+        TableSchema sourceSchema = TableSchema.builder().build();
+
+        List<SqlNode> derivedColumns =
+                Arrays.asList(
+                        metadataColumn("one", DataTypes.BOOLEAN(), true),
+                        metadataColumn("two", DataTypes.STRING(), "one", false));
+
+        Map<FeatureOption, MergingStrategy> mergingStrategies = getDefaultMergingStrategies();
+        mergingStrategies.put(FeatureOption.METADATA, MergingStrategy.INCLUDING);
+
+        thrown.expect(ValidationException.class);
+        thrown.expectMessage(

Review Comment:
   How about we add this validation logic to `DefaultSchemaResolver`? This way we avoid checking duplicate metadata keys at three locations and fail as early as possible.



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