Data Warehouse (DW) and Online Analytical Processing (OLAP) technologies are the core of current Decision Support Systems. Traditionally, a data warehouse has been a historical (and relatively static) repository of data collected from a wide variety of heterogeneous data sources by means of Extraction-Transformation-Loading (ETL) processes. The widespread deployment of both DWs and OLAP technologies is due to the intuitive representation of data provided to data analysts or managers in support of management decisions. Recently, the trend is that DWs become more and more dynamic, with near-real-time updates, and include more complex types of data. Research in data warehousing and OLAP has produced important technologies for the design, management and use of information systems for decision support. Much of the interest and success in this area can be attributed to the need for software and tools to improve data management and analysis given the large amounts of information that are being accumulated in corporate as well as scientific databases. Nevertheless, the high maturity of these technologies as well as new data needs or applications not only demand more capacity or storing necessities, but also new methods, models, techniques or architectures to satisfy these new needs. Some of the hot topics in data warehouse research include distributed data warehouses, web warehouses, data streams, real-time data warehouses, GIS/location-based services, biomedical data, integration of semi-structured and unstructured data, security/privacy and quality management. Like the previous successful DOLAP workshops, the DOLAP 2015 workshop aims to synergistically connect the research community and industry practitioners. It provides an international forum where both researchers and practitioners can share their findings in theoretical foundations, current methodologies, and practical experiences. DOLAP will focus on new research directions and emerging applications in DW & OLAP. We are expanding the scope of DOLAP to include work in bridging search engines and data warehouses.