fix: schema metadata retrieval when listing parquet table (apache#9134)

* fix: schema metadata retrieval when listing parquet table

* fix: modified code formatting

* fix: replaced unnecessary use of deref with as_ref

datafusion/core/src/datasource/listing/table.rs

@@ -548,7 +548,7 @@ impl ListingTable {
         })?;
 
         // Add the partition columns to the file schema
-        let mut builder = SchemaBuilder::from(file_schema.fields());
+        let mut builder = SchemaBuilder::from(file_schema.as_ref().to_owned());
         for (part_col_name, part_col_type) in &options.table_partition_cols {
             builder.push(Field::new(part_col_name, part_col_type.clone(), false));
         }

datafusion/core/tests/parquet/schema.rs

@@ -148,6 +148,10 @@ async fn schema_merge_can_preserve_metadata() {
         .read_parquet(&table_path, options.clone())
         .await
         .unwrap();
+
+    let actual = df.schema().metadata();
+    assert_eq!(actual.clone(), expected_metadata,);
+
     let actual = df.collect().await.unwrap();
 
     assert_batches_sorted_eq!(expected, &actual);
@@ -158,13 +162,12 @@ async fn schema_merge_can_preserve_metadata() {
         .await
         .unwrap();
 
-    let actual = ctx
-        .sql("SELECT * from t")
-        .await
-        .unwrap()
-        .collect()
-        .await
-        .unwrap();
+    let df = ctx.sql("SELECT * from t").await.unwrap();
+
+    let actual = df.schema().metadata();
+    assert_eq!(actual.clone(), expected_metadata);
+
+    let actual = df.collect().await.unwrap();
     assert_batches_sorted_eq!(expected, &actual);
     assert_metadata(&actual, &expected_metadata);
 }