Early exit on column normalisation to improve DataFrame performance

datafusion/core/src/dataframe/mod.rs

@@ -1801,7 +1801,8 @@ impl DataFrame {
             .iter()
             .map(|(qualifier, field)| {
                 if qualifier.eq(&qualifier_rename) && field.as_ref() == field_rename {
-                    col(Column::from((qualifier, field))).alias(new_name)
+                    col(Column::from((qualifier, field)))
+                        .alias_qualified(qualifier.cloned(), new_name)
                 } else {
                     col(Column::from((qualifier, field)))
                 }

datafusion/core/tests/dataframe/mod.rs

@@ -63,7 +63,7 @@ use datafusion::{assert_batches_eq, assert_batches_sorted_eq};
 use datafusion_catalog::TableProvider;
 use datafusion_common::{
     assert_contains, Constraint, Constraints, DataFusionError, ParamValues, ScalarValue,
-    UnnestOptions,
+    TableReference, UnnestOptions,
 };
 use datafusion_common_runtime::SpawnedTask;
 use datafusion_execution::config::SessionConfig;
@@ -1617,9 +1617,25 @@ async fn with_column_renamed() -> Result<()> {
         // accepts table qualifier
         .with_column_renamed("aggregate_test_100.c2", "two")?
         // no-op for missing column
-        .with_column_renamed("c4", "boom")?
-        .collect()
-        .await?;
+        .with_column_renamed("c4", "boom")?;
+
+    let references: Vec<_> = df_sum_renamed
+        .schema()
+        .iter()
+        .map(|(a, _)| a.cloned())
+        .collect();
+
+    assert_eq!(
+        references,
+        vec![
+            Some(TableReference::bare("aggregate_test_100")), // table name is preserved
+            Some(TableReference::bare("aggregate_test_100")),
+            Some(TableReference::bare("aggregate_test_100")),
+            None // total column
+        ]
+    );
+
+    let batches = &df_sum_renamed.collect().await?;
 
     assert_batches_sorted_eq!(
         [
@@ -1629,7 +1645,7 @@ async fn with_column_renamed() -> Result<()> {
             "| a   | 3   | -72 | -69   |",
             "+-----+-----+-----+-------+",
         ],
-        &df_sum_renamed
+        batches
     );
 
     Ok(())

datafusion/expr/src/logical_plan/builder.rs

@@ -834,10 +834,16 @@ impl LogicalPlanBuilder {
         plan: &LogicalPlan,
         column: impl Into<Column>,
     ) -> Result<Column> {
+        let column = column.into();
+        if column.relation.is_some() {
+            // column is already normalized
+            return Ok(column);
+        }
+
         let schema = plan.schema();
         let fallback_schemas = plan.fallback_normalize_schemas();
         let using_columns = plan.using_columns()?;
-        column.into().normalize_with_schemas_and_ambiguity_check(
+        column.normalize_with_schemas_and_ambiguity_check(
             &[&[schema], &fallback_schemas],
             &using_columns,
         )