jelly-1203 commented on a change in pull request #18017:
URL: https://github.com/apache/flink/pull/18017#discussion_r766554531
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File path:
flink-table/flink-table-planner/src/main/java/org/apache/flink/table/planner/operations/MergeTableLikeUtil.java
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@@ -426,6 +433,14 @@ private void appendDerivedColumns(
}
}
+ Set<String> physicalFieldNames =
physicalFieldNamesToTypes.keySet();
+ Set<String> metadataFieldNames =
metadataFieldNamesToTypes.keySet();
+ final Set<String> result = new
LinkedHashSet<>(physicalFieldNames);
+ result.retainAll(metadataFieldNames);
+ if (!result.isEmpty()) {
+ throw new ValidationException(
+ "A field name conflict exists between a field
of the regular type and a field of the Metadata type.");
+ }
Review comment:
> may be we can just check duplication when put the new Column to the
columns, at the end of this function?
hi @wenlong88
Thanks for your review and comment. I do not think duplication can be
checked when putting the new Column to the columns, at the end of this
function. The reasons are as follows:
1. If computeColumn or MetadataColumn uses overwrite's Merge strategy,
duplicate fields are allowed for the same type.
2. To add physical accessibleFieldNamesToTypes columns and metadata columns,
if metadataColumn before, and repeated physical column, leads to putAll,
Metadata columns overwrite duplicate physical columns, which can result in a
generated computeColumn that is not as expected.
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