A P2P Meta-index for Spatio-temporal Moving Object Databases

Abstract

Abstract. In this paper we propose a distributed meta-index using a peer-to-peer protocol to allow spatio-temporal queries of moving objects on a large set of distributed database servers. We present distribution and fault tolerance strategies of a meta-index that combines partial trace of object movements with aggregated data about the number of objects in the database servers. The degrees of distribution and fault tolerance were compared by using discrete-event simulators with demanding spatiotemporal workloads. The results show that the distributed meta-index using Chord provides good performance, scalability and fault tolerance.

Complex Queries for Moving Object Databases in DHT-Based Systems

“…With the purpose of answering object-location queries and aggregation queries, we propose in [6] two strategies for distributing the meta-index data with Chord protocol and using the available bandwidth effectively. On one hand, we introduce the concept of MSB (Most Significant Bits) to map moving object trace data to Chord keys.…”

“…S-messages also carry aggregated data about the number of objects per type that were found by the robots at specific servers and time instants, which are stored in all peers crossed until finding the destination peers. The idea behind this strategy is to have an overall view of the global statistics of the system in each peer [6]. T-messages (message 2 in Figure 1) transfer composite objects from the entry peers to the destination peers.…”

“…We have reported work on object-location queries and aggregation queries, first for a centralized meta-index in [8], and then for a distributed meta-index on a p2p network in [6]. In this paper we extend the p2p meta-index proposed in [6] to include spatio-temporal range queries and top-k object queries.…”

“…In this paper we extend the p2p meta-index proposed in [6] to include spatio-temporal range queries and top-k object queries. To do so, we complement the data distribution in [6] and design search algorithms for these queries. In addition, we propose a fully distributed scheme to perform polling by assigning this task to a sub-set of peers.…”

A meta-index for querying distributed moving object database servers

“…We have also studied crawling and indexing in the context of P2P environments in [14,15]. The present paper focuses on the centralized query processing in the meta-index, which resembles the services provided by large Web search engines.…”