should be it

external/duckdb/extension/parquet/include/parquet_field_id.hpp

@@ -0,0 +1,39 @@
+#pragma once
+
+#include "duckdb/common/serializer/buffered_file_writer.hpp"
+#include "duckdb/common/case_insensitive_map.hpp"
+
+namespace duckdb {
+
+struct FieldID;
+struct ChildFieldIDs {
+	ChildFieldIDs();
+	ChildFieldIDs Copy() const;
+	unique_ptr<case_insensitive_map_t<FieldID>> ids;
+
+	void Serialize(Serializer &serializer) const;
+	static ChildFieldIDs Deserialize(Deserializer &source);
+};
+
+struct FieldID {
+public:
+	static constexpr const auto DUCKDB_FIELD_ID = "__duckdb_field_id";
+	FieldID();
+	explicit FieldID(int32_t field_id);
+	FieldID Copy() const;
+	bool set;
+	int32_t field_id;
+	ChildFieldIDs child_field_ids;
+
+	void Serialize(Serializer &serializer) const;
+	static FieldID Deserialize(Deserializer &source);
+
+public:
+	static void GenerateFieldIDs(ChildFieldIDs &field_ids, idx_t &field_id, const vector<string> &names,
+	                             const vector<LogicalType> &sql_types);
+	static void GetFieldIDs(const Value &field_ids_value, ChildFieldIDs &field_ids,
+	                        unordered_set<uint32_t> &unique_field_ids,
+	                        const case_insensitive_map_t<LogicalType> &name_to_type_map);
+};
+
+} // namespace duckdb