Hi Dirk,
The question is quite generic and may need additional information. Do you mean the queries to be written manually or some modeling best practices that would generate efficient queries.
I am not sure what you mean by query structure design. But regarding performance improvement aspects, please refer to the some of the documents included in the zip file at the following location.
http://www.saphana.com/docs/DOC-2171
This will give you a good idea on performance and design practices for the same.
Regards,
Ravi