Indexing Large Trajectory Data Sets With SETI

With the rapid increase in the use of inexpensive, location-aware sensors in a variety of new applications, large amounts of time-sequenced location data will soon be accumulated. Efficient indexing techniques for managing these large volumes of trajectory data sets are urgently needed. The key requirements for a good trajectory indexing technique is that it must support both searches and inserts efficiently. This paper proposes a new indexing mechanism called SETI, a Scalable and Efficient Trajectory Index, that meets these requirements. SETI uses a simple two-level index structure to decouple the indexing of the spatial and the temporal dimensions. This decoupling makes both searches and inserts very efficient. Based on an actual implementation, we demonstrate that SETI clearly outperforms two previously proposed trajectory indexing mechanisms, namely the 3D R-tree and the TB-tree. Unlike previously proposed trajectory indexing structures, SETI is a logical indexing structure that uses existing spatial indexing structures, such as R-trees, without any modifications. Consequently, DBMSs that currently support R-trees can easily implement SETI, making it a both a practical and an efficient choice for indexing trajectory data sets. ∗This work is supported in part by NSF under grant IIS-0093059, and by an IBM Faculty Award. Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the VLDB copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Very Large Data Base Endowment. To copy otherwise, or to republish, requires a fee and/or special permission from the Endowment. Proceedings of the 2003 CIDR Conference