1. Denodo and Cisco both are offering data virtualization technologies .
2.The products give you the capability to add a middle layer over different data sources ( RDBMS like Oracle , sqlserver , Excel , XML etc). You can build views in this middle layer. There are tuning opportunities up to a certain extent so the views are efficient.
3. You would need dedicated admin team to be able to understand the capabilities of the tool and implement the business requirements. The admin team also need support from business analysts who know the different data sources very well . This is the main criteria to be able to define performant views.
4.Datavirtualization tools are not efficient if the amount of data that would need to be pulled into the middle layer is huge . Even though the tools allow to push down the filter criteria to the individual data sources , if the join criteria requires huge data to be pulled into the middle layer then the queries on the views won’t be performant .
5. Having evaluated both Denodo and Cisco , my preference is for Denodo as it is more user friendly and developer friendly.
