kosiew commented on code in PR #16583:
URL: https://github.com/apache/datafusion/pull/16583#discussion_r2181911243
##########
datafusion/core/src/datasource/listing/table.rs:
##########
@@ -894,6 +1047,81 @@ impl ListingTable {
self.schema_source
}
+ /// Set the [`SchemaAdapterFactory`] for this [`ListingTable`]
+ ///
+ /// The schema adapter factory is used to create schema adapters that can
+ /// handle schema evolution and type conversions when reading files with
+ /// different schemas than the table schema.
+ ///
+ /// # Example: Adding Schema Evolution Support
+ /// ```rust
+ /// # use std::sync::Arc;
+ /// # use datafusion::datasource::listing::{ListingTable,
ListingTableConfig, ListingOptions, ListingTableUrl};
+ /// # use datafusion::datasource::schema_adapter::{SchemaAdapterFactory,
SchemaAdapter};
+ /// # use datafusion::datasource::file_format::parquet::ParquetFormat;
+ /// # use arrow::datatypes::{SchemaRef, Schema, Field, DataType};
+ /// # #[derive(Debug)]
+ /// # struct EvolutionAdapterFactory;
+ /// # impl SchemaAdapterFactory for EvolutionAdapterFactory {
+ /// # fn create(&self, _projected_table_schema: SchemaRef,
_file_schema: SchemaRef) -> Box<dyn SchemaAdapter> {
+ /// # unimplemented!()
+ /// # }
+ /// # }
+ /// # let table_path =
ListingTableUrl::parse("file:///path/to/data").unwrap();
+ /// # let options =
ListingOptions::new(Arc::new(ParquetFormat::default()));
+ /// # let schema = Arc::new(Schema::new(vec![Field::new("id",
DataType::Int64, false)]));
+ /// # let config =
ListingTableConfig::new(table_path).with_listing_options(options).with_schema(schema);
+ /// # let table = ListingTable::try_new(config).unwrap();
+ /// let table_with_evolution = table
+ /// .with_schema_adapter_factory(Arc::new(EvolutionAdapterFactory));
+ /// ```
+ pub fn with_schema_adapter_factory(
+ self,
+ schema_adapter_factory: Arc<dyn SchemaAdapterFactory>,
+ ) -> Self {
+ Self {
+ schema_adapter_factory: Some(schema_adapter_factory),
+ ..self
+ }
+ }
+
+ /// Get the [`SchemaAdapterFactory`] for this table
+ pub fn schema_adapter_factory(&self) -> Option<&Arc<dyn
SchemaAdapterFactory>> {
+ self.schema_adapter_factory.as_ref()
+ }
+
+ /// Creates a schema adapter for mapping between file and table schemas
+ ///
+ /// Uses the configured schema adapter factory if available, otherwise
falls back
+ /// to the default implementation.
+ fn create_schema_adapter(&self) -> Box<dyn SchemaAdapter> {
+ let table_schema = self.schema();
+ match &self.schema_adapter_factory {
+ Some(factory) => {
+ factory.create(Arc::clone(&table_schema),
Arc::clone(&table_schema))
Review Comment:
Added create_with_projected_schema to the api
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