dwsmith1983 commented on code in PR #5654:
URL: https://github.com/apache/datafusion-comet/pull/5654#discussion_r4100241893
##########
native/core/src/parquet/schema_adapter.rs:
##########
@@ -1009,10 +1083,84 @@ impl PhysicalExprAdapterFactory for
SparkPhysicalExprAdapterFactory {
id_duplicate_roots,
logical_folded,
physical_folded,
+ nested_mappings,
+ root_id_ambiguities,
}))
}
}
+/// Per logical field name, the mapping of its nested type against its
physical counterpart,
+/// or the ambiguity Spark reports for it. Only fields whose type holds a
struct are listed.
+type NestedMappings = HashMap<String, Result<Arc<FieldMapping>, SparkError>>;
+
+/// Per logical field name, the `_LEGACY_ERROR_TEMP_2094` ambiguity of a root
field whose id
+/// matches more than one physical root field. Only ambiguous fields are
listed.
+type RootIdAmbiguities = HashMap<String, SparkError>;
+
+fn type_holds_struct(data_type: &DataType) -> bool {
+ // The resolver and converter in `parquet_support` decide which types are
lists through
+ // the same helper, so this walk descends into exactly the lists they map.
+ if let Some(element) = list_element_field(data_type) {
+ return type_holds_struct(element.data_type());
+ }
+ match data_type {
+ DataType::Struct(_) => true,
+ DataType::Map(f, _) => type_holds_struct(f.data_type()),
+ _ => false,
+ }
+}
+
+/// Resolve the nested mapping of every logical field whose type holds a
struct and that has
+/// a physical counterpart. Returns `None` when no field qualifies, so flat
reads build
+/// nothing here. Ambiguities are kept per field rather than raised: Spark
validates only
+/// the fields a read requests, and `rewrite` sees which ones those are.
+fn resolve_nested_mappings(
Review Comment:
Dropped, with `NestedMappings`, `type_holds_struct`, `field_mapping_for`,
`check_opaque_decode` and the nested block in `rewrite`. `check_conversion` on
main already runs `match_struct_fields` before every non-Variant cast, and with
#6004 declining repeated requested ids an ambiguous read always gets a cast, so
the nested duplicate-id error fires from there at plan time. The follow-up PR
will build the once-per-file mapping where `CometCastColumnExpr` is built, from
its own `(input_field, target_field)`.
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