kosiew commented on code in PR #16371: URL: https://github.com/apache/datafusion/pull/16371#discussion_r2157884676
########## datafusion/datasource/src/nested_schema_adapter/adapter.rs: ########## @@ -0,0 +1,93 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +use crate::schema_adapter::{ + create_field_mapping, SchemaAdapter, SchemaMapper, SchemaMapping, +}; +use arrow::{ + array::ArrayRef, + datatypes::{DataType::Struct, Field, Schema, SchemaRef}, +}; +use datafusion_common::nested_struct::adapt_column; +use datafusion_common::Result; +use std::sync::Arc; + +/// A SchemaAdapter that handles schema evolution for nested struct types +#[derive(Debug, Clone)] +pub struct NestedStructSchemaAdapter { + /// The schema for the table, projected to include only the fields being output (projected) by the + /// associated ParquetSource + projected_table_schema: SchemaRef, + /// The entire table schema for the table we're using this to adapt. + /// + /// This is used to evaluate any filters pushed down into the scan + /// which may refer to columns that are not referred to anywhere + /// else in the plan. + table_schema: SchemaRef, +} + +impl NestedStructSchemaAdapter { + /// Create a new NestedStructSchemaAdapter with the target schema + pub fn new(projected_table_schema: SchemaRef, table_schema: SchemaRef) -> Self { + Self { + projected_table_schema, + table_schema, + } + } + + pub fn projected_table_schema(&self) -> &Schema { + self.projected_table_schema.as_ref() + } + + pub fn table_schema(&self) -> &Schema { + self.table_schema.as_ref() + } +} + +impl SchemaAdapter for NestedStructSchemaAdapter { + fn map_column_index(&self, index: usize, file_schema: &Schema) -> Option<usize> { + let field_name = self.table_schema.field(index).name(); + file_schema.index_of(field_name).ok() + } + + fn map_schema( + &self, + file_schema: &Schema, + ) -> Result<(Arc<dyn SchemaMapper>, Vec<usize>)> { + let (field_mappings, projection) = create_field_mapping( + file_schema, + &self.projected_table_schema, + |file_field, table_field| { + // Special handling for struct fields - always include them even if the + // internal structure differs, as we'll adapt them later + match (file_field.data_type(), table_field.data_type()) { + (Struct(_), Struct(_)) => Ok(true), Review Comment: Thanks for pointing this out. I'll add code to validate compatibility. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: github-unsubscr...@datafusion.apache.org For additional commands, e-mail: github-h...@datafusion.apache.org
