A Universal Distributed Indexing Scheme for Data Centers with Tree-Like Topologies

The indices in the distributed storage systems manage the stored data and support diverse queries efficiently. Secondary index, the index built on the attributes other than the primary key, facilitates a variety of queries for different purposes. In this paper, we propose U²-Tree, a universal distributed secondary indexing scheme built on cloud storage systems with tree-like topologies. U²-Tree is composed of two layers, the global index and the local index. We build the local index according to the local data features, and then assign the potential indexing range of the global index for each host. After that, we use several techniques to publish the meta-data about local index to the global index host. The global index is then constructed based on the collected intervals. We take advantage of the topological properties of tree-like topologies, introduce and compare the detailed optimization techniques in the construction of two-layer indexing scheme. Furthermore, we discuss the index updating, index tuning, and the fault tolerance of U²-Tree. Finally, we propose numerical experiments to evaluate the performance of U²-Tree. The universal indexing scheme provides a general approach for secondary index on data centers with tree-like topologies. Moreover, many techniques and conclusions can be applied to other DCN topologies.