Efficient and Progressive Algorithms for Distributed Skyline Queries over Uncertain Data

Abstract

The skyline operator has received considerable attention from the database community, due to its importance in many applications including multi-criteria decision making, preference answering, and so forth. In many applications where uncertain data are inherently exist, i.e., data collected from different sources in distributed locations are usually with imprecise measurements, and thus exhibit kind of uncertainty. Taking into account the network delay and economic cost associated with sharing and communicating large amounts of distributed data over an internet, an important problem in this scenario is to retrieve the global skyline tuples from all the distributed local sites with minimum communication cost. Based on the well known notation of the probabilistic skyline query over centralized uncertain data, in this paper, for the first time, we propose the notation of distributed skyline queries over uncertain data. Furthermore, two communication-and computation-efficient algorithms are proposed to retrieve the qualified skylines from distributed local sites. Extensive experiments have been conducted to verify the efficiency and the effectiveness of our algorithms with both the synthetic and real data sets.

Efficient and scalable continuous skyline monitoring in two-tier streaming settings

“…Rocha-Junior [22] proposed a framework that generates distributed execution plans for skyline queries over static data across a large number of servers. Ding and Jin [7] designed skyline algorithms for distributed uncertain data. This paper is focused on dynamic data streams that differ from the settings in these previous works.…”

“…Second, those global skyline points that are no longer local skyline points on the updating site are removed from the global skyline (line 6). Next, if the message type is not UPT_MSG_Case_8, those false positive global skyline points that are no longer local skyline points on the updating site are removed from the false positive skyline array (lines [7][8].…”

A survey of skyline processing in highly distributed environments

“…Skyline queries over uncertain data have been studied in centralized [30] but also in distributed [15] domains. The distributed system employed in [15] is similar to the fully connected network topology.…”

“…Skyline queries over uncertain data have been studied in centralized [30] but also in distributed [15] domains. The distributed system employed in [15] is similar to the fully connected network topology. Nevertheless, the probabilistic skyline query differs substantially from the skyline query and different challenges arise for efficient processing of distributed probabilistic skyline queries.…”

“…In [15], the DSUD algorithm aims to reduce the number of transmitted data objects by using multiple communication round trips. Initially, only the most promising point (in terms of local probability) is transferred from each server to the coordinator.…”