should be it

external/duckdb/extension/tpch/include/tpch_extension.hpp

@@ -0,0 +1,27 @@
+//===----------------------------------------------------------------------===//
+//                         DuckDB
+//
+// tpch_extension.hpp
+//
+//
+//===----------------------------------------------------------------------===//
+
+#pragma once
+
+#include "duckdb.hpp"
+
+namespace duckdb {
+
+class TpchExtension : public Extension {
+public:
+	void Load(ExtensionLoader &loader) override;
+	std::string Name() override;
+	std::string Version() const override;
+
+	//! Gets the specified TPC-H Query number as a string
+	static std::string GetQuery(int query);
+	//! Returns the CSV answer of a TPC-H query
+	static std::string GetAnswer(double sf, int query);
+};
+
+} // namespace duckdb