We are considering using Cognos BI to create reports stored in our Oracle and SQL Server databases. Report designs have not been finalised but joins between databases are likely to be unavoidable. What would be the best strategy to store and access the data in order to achieve performance and ease of development? Is it better to collocate the needed tables or let Framework Manager handle the joins first and tackle performance problems later? Are there risk factors that we especially need to pay attention to in such an environment?