alamb commented on code in PR #19128:
URL: https://github.com/apache/datafusion/pull/19128#discussion_r2603423250
##########
datafusion-examples/examples/custom_data_source/default_column_values.rs:
##########
@@ -304,74 +303,32 @@ struct DefaultValuePhysicalExprAdapter {
impl PhysicalExprAdapter for DefaultValuePhysicalExprAdapter {
fn rewrite(&self, expr: Arc<dyn PhysicalExpr>) -> Result<Arc<dyn
PhysicalExpr>> {
- // First try our custom default value injection for missing columns
- let rewritten = expr
- .transform(|expr| {
- self.inject_default_values(
- expr,
- &self.logical_file_schema,
- &self.physical_file_schema,
- )
- })
- .data()?;
-
- // Then apply the default adapter as a fallback to handle standard
schema differences
- // like type casting, etc.
- self.default_adapter.rewrite(rewritten)
- }
-}
-
-impl DefaultValuePhysicalExprAdapter {
- fn inject_default_values(
- &self,
- expr: Arc<dyn PhysicalExpr>,
- logical_file_schema: &Schema,
- physical_file_schema: &Schema,
- ) -> Result<Transformed<Arc<dyn PhysicalExpr>>> {
- if let Some(column) = expr.as_any().downcast_ref::<Column>() {
- let column_name = column.name();
-
- // Check if this column exists in the physical schema
- if physical_file_schema.index_of(column_name).is_err() {
- // Column is missing from physical schema, check if logical
schema has a default
- if let Ok(logical_field) =
- logical_file_schema.field_with_name(column_name)
- {
- if let Some(default_value_str) =
-
logical_field.metadata().get(DEFAULT_VALUE_METADATA_KEY)
- {
- // Create a string literal and wrap it in a cast
expression
- let default_literal = self.create_default_value_expr(
- default_value_str,
- logical_field.data_type(),
- )?;
- return Ok(Transformed::yes(default_literal));
- }
- }
+ // Pre-compute replacements for missing columns with default values
Review Comment:
this is great
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