[GitHub] [calcite] rubenada commented on a diff in pull request #2791: [CALCITE-5134] Queries with subquery inside select list does not work if subquery uses table from left join

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

rubenada commented on code in PR #2791:
URL: https://github.com/apache/calcite/pull/2791#discussion_r898113844


##########
core/src/main/java/org/apache/calcite/sql2rel/SqlToRelConverter.java:
##########
@@ -4883,7 +4883,14 @@ void setRoot(List<RelNode> inputs) {
           int i = 0;
           int offset = 0;
           for (SqlValidatorNamespace c : ancestorScope1.getChildren()) {
-            builder.addAll(c.getRowType().getFieldList());
+            final boolean isNullable = ancestorScope1.children.get(i).isNullable();

Review Comment:
   Thanks for the PR @libenchao .
   I'm not the most expert on the impacted classes, but I guess some people might frown upon making `ScopeChild` public just for this fix. What about...
   - Leaving `ScopeChild` unchanged
   - Add a new method in `ListScope`:
   ```
     public boolean isChildNullable(int i) {
       return children.get(i).nullable;
     }
   ```
   - Changing the `if` condition on the `SqlToRelConverter` fix code to use this method:
   ```
   for (SqlValidatorNamespace c : ancestorScope1.getChildren()) {
     if (ancestorScope1.isChildNullable(i)) {
       for (final RelDataTypeField f : c.getRowType().getFieldList()) {
         builder.add(f.getName(), typeFactory.createTypeWithNullability(f.getType(), true));
       }
     } else {
       builder.addAll(c.getRowType().getFieldList());
     }
     ...
   ```              
   In my opinion, it would be a slightly cleaner solution than the current proposal, WDYT?



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