[GitHub] [arrow-datafusion] xudong963 commented on a change in pull request #1067: fix subquery alias

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

xudong963 commented on a change in pull request #1067:
URL: https://github.com/apache/arrow-datafusion/pull/1067#discussion_r722927932



##########
File path: datafusion/src/sql/planner.rs
##########
@@ -522,21 +521,43 @@ impl<'a, S: ContextProvider> SqlToRel<'a, S> {
                             name
                         ))),
                     }?,
-                    columns_alias,
+                    alias,
                 )
             }
             TableFactor::Derived {
                 subquery, alias, ..
-            } => (
-                self.query_to_plan_with_alias(
+            } => {
+                // if alias is None, return Err
+                if alias.is_none() {
+                    return Err(DataFusionError::Plan(
+                        "subquery in FROM must have an alias".parse().unwrap(),
+                    ));
+                }
+                let logical_plan = self.query_to_plan_with_alias(
                     subquery,
                     alias.as_ref().map(|a| a.name.value.to_string()),
                     ctes,
-                )?,
-                alias.clone().map(|x| x.columns),
-            ),
+                )?;
+                let schema = logical_plan.schema();

Review comment:
       > My guess is the projection won't work if the schema is still referencing the original qualifier, i.e. projection asked for `b.id`, but the input plan schema only has `customer.id`, resulting in runtime error.
   
   yep!  cc @alamb 




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