[GitHub] [arrow-datafusion] Dandandan commented on a change in pull request #375: add window expression stream, delegated window aggregation, and a basic structure for row_number

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

Dandandan commented on a change in pull request #375:
URL: https://github.com/apache/arrow-datafusion/pull/375#discussion_r637600299



##########
File path: datafusion/src/physical_plan/windows.rs
##########
@@ -57,25 +74,81 @@ pub fn create_window_expr(
                 name,
             )?,
         })),
-        WindowFunction::BuiltInWindowFunction(fun) => {
-            Err(DataFusionError::NotImplemented(format!(
-                "window function with {:?} not implemented",
-                fun
-            )))
-        }
+        WindowFunction::BuiltInWindowFunction(fun) => Ok(Arc::new(BuiltInWindowExpr {
+            window: create_built_in_window_expr(fun, args, input_schema, name)?,
+        })),
+    }
+}
+
+fn create_built_in_window_expr(
+    fun: &BuiltInWindowFunction,
+    _args: &[Arc<dyn PhysicalExpr>],
+    _input_schema: &Schema,
+    name: String,
+) -> Result<Arc<dyn BuiltInWindowFunctionExpr>> {
+    match fun {
+        BuiltInWindowFunction::RowNumber => Ok(Arc::new(RowNumber::new(name))),
+        _ => Err(DataFusionError::NotImplemented(format!(
+            "window function with {:?} not yet implemented",

Review comment:
       ```suggestion
               "Window function with {:?} not yet implemented",
   ```




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