Automatic primary key for BDB tables

sql/field.h

@@ -44,7 +44,7 @@ public:
   uint8		null_bit;		// And position to it
   struct st_table *table;		// Pointer for table
   ulong query_id;			// For quick test of used fields
-  key_map key_start,part_of_key;	// Which keys a field is in
+  key_map key_start,part_of_key;	// Key is part of these keys.
   const char *table_name,*field_name;
   utype unireg_check;
   uint32 field_length;			// Length of field