[GitHub] [arrow-datafusion] alamb commented on a change in pull request #547: support table alias in join clause

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

alamb commented on a change in pull request #547:
URL: https://github.com/apache/arrow-datafusion/pull/547#discussion_r650511150



##########
File path: datafusion/src/sql/planner.rs
##########
@@ -424,17 +424,24 @@ impl<'a, S: ContextProvider> SqlToRel<'a, S> {
         ctes: &mut HashMap<String, LogicalPlan>,
     ) -> Result<LogicalPlan> {
         match relation {
-            TableFactor::Table { name, .. } => {
+            TableFactor::Table { name, alias, .. } => {
                 let table_name = name.to_string();
                 let cte = ctes.get(&table_name);
                 match (
                     cte,
                     self.schema_provider.get_table_provider(name.try_into()?),
                 ) {
                     (Some(cte_plan), _) => Ok(cte_plan.clone()),
-                    (_, Some(provider)) => {
-                        LogicalPlanBuilder::scan(&table_name, provider, None)?.build()
-                    }
+                    (_, Some(provider)) => LogicalPlanBuilder::scan(
+                        // take alias into account to support `JOIN table1 as table2`
+                        alias
+                            .as_ref()
+                            .map(|a| a.name.value.as_str())
+                            .unwrap_or(&table_name),
+                        provider,
+                        None,
+                    )?
+                    .build(),
                     (_, None) => Err(DataFusionError::Plan(format!(

Review comment:
       ```suggestion
                       (None, None) => Err(DataFusionError::Plan(format!(
   ```
   Might make it clearer that now both branches are covered?




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