Compressed Aggregations for mobile OLAP

This chapter introduces the mobile Dwarf (m-Dwarf), a compressed data cube physical structure, with no loss of semantic information and explicitly designed for mobile environments [114]. m-Dwarfs are integrated in the FCLOS architecture. Due to the achieved compression, a substantial reduction of access time, energy consumption and bandwidth utilization against architectures which transmit STs is observed. The chapter is structured as follows: Section 8.1 gives the motivation behind this work. In Section 8.2, we present related work in the area of data cube physical structures and explain the involved tradeoff in the mOLAP domain. Section 8.3 presents the m-Dwarf data cube physical structure and provides an extensive performance evaluation, while Section 8.4 describes how m-Dwarfs can be seamlessly integrated in the FCLOS architecture. In Section 8.5, we present the results of the experimental evaluation transmitting m-Dwarfs in mOLAP applications. Finally, Section 8.6 provides an overview of the examined physical structures.