[GitHub] [beam] apilloud commented on a change in pull request #12550: Follow the same way that BigQuery handles unspecified or duplicate ZetaSQL STRUCT field name

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

apilloud commented on a change in pull request #12550:
URL: https://github.com/apache/beam/pull/12550#discussion_r469461524



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File path: sdks/java/extensions/sql/zetasql/src/main/java/org/apache/beam/sdk/extensions/sql/zetasql/ZetaSqlCalciteTranslationUtils.java
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@@ -180,12 +182,19 @@ private static RelDataType toCalciteStructType(
 
   private static List<String> getFieldNameList(List<StructField> fields) {
     ImmutableList.Builder<String> b = ImmutableList.builder();
+    Set<String> usedName = new HashSet<>();
     for (int i = 0; i < fields.size(); i++) {
       String name = fields.get(i).getName();
-      if ("".equals(name)) {
-        name = "$col" + i; // avoid empty field names because Beam does not allow duplicate names
+      // Follow the same way that BigQuery handles unspecified or duplicate field name
+      if ("".equals(name) || usedName.contains(name)) {

Review comment:
       This does not actually match the behavior of BigQuery. To match BigQuery you should remove the `HashSet` and instead replace anything starting with `_field_` with the correct index for that column.
   
   (In BigQuery, this condition would be `"".equals(name) || name.startsWith("_field_")`)




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