Large volumes of data is generated from the increasing num-ber of sensor networks and smart devices. Such data is generated and published in multiple formats, thus highlighting the significance of inter-operability for the success of what has come to be known as the Internet of Things (IoT). The BT Hypercat Data Hub provides a focal point for the sharing and consumption of available datasets from a wide range of sources. In this work, we present a series of optimizations applied on the BT Hypercat Data Hub that enabled scalable SPARQL query answering over relational databases and an access control mechanism that filters SPARQL results based on user's subscriptions.