Make Expr::alias and alias_qualified smarter by calling unalias

I can't imagine a use case where we want to have double aliasing
coralogix · Feb 20, 2025 · 7ca35e8 · 7ca35e8
1 parent 2f40f6c
commit 7ca35e8
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Showing 2 changed files with 3 additions and 3 deletions.
diff --git a/datafusion/expr/src/expr.rs b/datafusion/expr/src/expr.rs
@@ -1276,7 +1276,7 @@ impl Expr {
 
     /// Return `self AS name` alias expression
     pub fn alias(self, name: impl Into<String>) -> Expr {
-        Expr::Alias(Alias::new(self, None::<&str>, name.into()))
+        Expr::Alias(Alias::new(self.unalias(), None::<TableReference>, name))
     }
 
     /// Return `self AS name` alias expression with a specific qualifier
@@ -1285,7 +1285,7 @@ impl Expr {
         relation: Option<impl Into<TableReference>>,
         name: impl Into<String>,
     ) -> Expr {
-        Expr::Alias(Alias::new(self, relation, name.into()))
+        Expr::Alias(Alias::new(self.unalias(), relation, name))
     }
 
     /// Remove an alias from an expression if one exists.

diff --git a/datafusion/optimizer/src/analyzer/type_coercion.rs b/datafusion/optimizer/src/analyzer/type_coercion.rs
@@ -1013,7 +1013,7 @@ fn project_with_column_index(
         .enumerate()
         .map(|(i, e)| match e {
             Expr::Alias(Alias { ref name, .. }) if name != schema.field(i).name() => {
-                Ok(e.unalias().alias(schema.field(i).name()))
+                Ok(e.alias(schema.field(i).name()))
             }
             Expr::Column(Column {
                 relation: _,