--- a/include/relpipe/writer/RelationalWriter.h	Mon Sep 03 23:41:29 2018 +0200
+++ b/include/relpipe/writer/RelationalWriter.h	Sun Sep 09 23:20:57 2018 +0200
@@ -5,6 +5,7 @@
 
 #include "typedefs.h"
 #include "TypeId.h"
+#include "AttributeMetadata.h"
 
 namespace relpipe {
 namespace writer {
@@ -28,7 +29,7 @@
 	 * @param attributes list of attributes (columns) containing their names and types
 	 * @param writeHeader header might be omitted – when appending new records to a stream alreaready containing the header
 	 */
-	virtual void startRelation(string_t name, std::vector<std::pair<string_t, TypeId>> attributes, boolean_t writeHeader) = 0;
+	virtual void startRelation(string_t name, std::vector<AttributeMetadata> attributes, boolean_t writeHeader) = 0;
 
 	/**
 	 * Writes a single attribute.