[GitHub] [arrow-datafusion] e1ijah1 commented on a diff in pull request #6458: feat: support type coercion in Parquet Reader

["e1ijah1 (via GitHub)" <gi...@apache.org>]

e1ijah1 commented on code in PR #6458:
URL: https://github.com/apache/arrow-datafusion/pull/6458#discussion_r1214279677


##########
datafusion/core/src/physical_plan/file_format/mod.rs:
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@@ -489,38 +491,93 @@ impl SchemaAdapter {
             field_mappings,
         })
     }
+
+    /// Creates a `SchemaMapping` that can be used to cast or map the columns from the file schema
+    /// to the table schema, taking into account the provided projections.
+    pub fn map_schema_with_projection(

Review Comment:
   I would like to suggest that `map_schema_with_projection` may not be directly implemented as `self.map_schema(file_schema.project(projections))`. In the `evolved_schema` test, some columns are processed as null arrays in `SchemaMapping.map_batch`. However, we could consider performing a projection on `table_schema` when creating `SchemaAdapter`.



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