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Spatial Keyword Query Processing: An Experimental Evaluation
"... Geo-textual indices play an important role in spatial keyword querying. The existing geo-textual indices have not been compared systematically under the same experimental framework. This makes it difficult to determine which indexing technique best supports specific functionality. We provide an all- ..."
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Cited by 17 (3 self)
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Geo-textual indices play an important role in spatial keyword querying. The existing geo-textual indices have not been compared systematically under the same experimental framework. This makes it difficult to determine which indexing technique best supports specific functionality. We provide an all-around survey of 12 stateof-the-art geo-textual indices. We propose a benchmark that enables the comparison of the spatial keyword query performance. We also report on the findings obtained when applying the benchmark to the indices, thus uncovering new insights that may guide index selection as well as further research. 1.
Location-aware Publish/Subscribe
- KDD'13
, 2013
"... Location-based services have become widely available on mobile devices. Existing methods employ a pull model or user-initiated model, where a user issues a query to a server which replies with location-aware answers. To provide users with instant replies, a push model or server-initiated model is be ..."
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Cited by 10 (2 self)
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Location-based services have become widely available on mobile devices. Existing methods employ a pull model or user-initiated model, where a user issues a query to a server which replies with location-aware answers. To provide users with instant replies, a push model or server-initiated model is becoming an inevitable computing model in the next-generation location-based services. In the push model, subscribers register spatio-textual subscriptions to capture their interests, and publishers post spatio-textual messages. This calls for a high-performance location-aware publish/subscribe system to deliver publishers’ messages to relevant subscribers. In this paper, we address the research challenges that arise in designing a location-aware publish/subscribe system. We propose an R-tree based index structure by integrating textual descriptions into R-tree nodes. We devise efficient filtering algorithms and develop effective pruning techniques to improve filtering efficiency. Experimental results show that our method achieves high performance. For example, our method can filter 500 tweets in a second for 10 million registered subscriptions on a commodity computer.
Location-aware instant search
- In CIKM, 2012. SIGMOD Record
, 2013
"... Location-Based Services (LBS) have been widely accepted by mobile users recently. Existing LBS-based systems require users to type in complete keywords. However for mobile users it is rather difficult to type in complete keywords on mobile devices. To alleviate this problem, in this paper we study t ..."
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Cited by 7 (3 self)
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Location-Based Services (LBS) have been widely accepted by mobile users recently. Existing LBS-based systems require users to type in complete keywords. However for mobile users it is rather difficult to type in complete keywords on mobile devices. To alleviate this problem, in this paper we study the location-aware instant search problem, which returns users location-aware answers as users type in queries letter by letter. The main challenge is to achieve high interactive speed. To address this challenge, in this paper we propose a novel index structure, prefixregion tree (called PR-Tree), to efficiently support locationaware instant search. PR-Tree is a tree-based index structure which seamlessly integrates the textual description and spatial information to index the spatial data. Using the PR-Tree, we develop efficient algorithms to support single prefix queries and multi-keyword queries. Experiments show that our method achieves high performance and significantly outperforms state-of-the-art methods.
TsingNUS: A location-based service system towards live city (demo
- In SIGMOD
, 2013
"... We present our system towards live city, called TsingNUS, aiming to provide users with more user-friendly locationaware search experiences. TsingNUS crawls location-based user-generated content from the Web (e.g., Foursquare and Twitter), cleans and integrates them to provide users with rich well-st ..."
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Cited by 3 (1 self)
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We present our system towards live city, called TsingNUS, aiming to provide users with more user-friendly locationaware search experiences. TsingNUS crawls location-based user-generated content from the Web (e.g., Foursquare and Twitter), cleans and integrates them to provide users with rich well-structured data. TsingNUS provides three userfriendly search paradigms: location-aware instant search, locationaware similarity search and direction-aware search. Instant search returns relevant answers instantly as users type in queries letter by letter, which can help users to save typing efforts significantly. Location-aware similarity search enables fuzzy matching between queries and the underlying data, which can tolerate typing errors. The two features boost the search performance and improve the experiences for mobile users who often misspell the keywords due to the limitation of the mobile phone’s keyboard. In addition, users have direction-aware search requirements in many applications. For example, a driver on the highway wants to find the nearest gas station or restaurant. She has a search requirement that the answers should be in front of her driving direction. TsingNUS enables direction-aware search to address this problem and allows users to search in specific directions. Moreover, TsingNUS incorporates continuous search to efficiently support continuously moving queries in a client-server system which can reduce the number of queries submitted to the server and communication cost between the client and server. We have implemented and deployed a system which has been commonly used and widely accepted.
Z.: Location-aware pub/sub system: When continuous moving queries meet dynamic event streams
- In: SIGMOD 2015
, 2015
"... In this paper, we propose a new location-aware pub/sub system, Elaps, that continuously monitors moving users subscribing to dy-namic event streams from social media and E-commerce applica-tions. Users are notified instantly when there is a matching event nearby. To the best of our knowledge, Elaps ..."
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Cited by 3 (0 self)
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In this paper, we propose a new location-aware pub/sub system, Elaps, that continuously monitors moving users subscribing to dy-namic event streams from social media and E-commerce applica-tions. Users are notified instantly when there is a matching event nearby. To the best of our knowledge, Elaps is the first to take into account continuous moving queries against dynamic event streams. Like existing works on continuous moving query processing, Elaps employs the concept of safe region to reduce communication over-head. However, unlike existing works which assume data from publishers are static, updates to safe regions may be triggered by newly arrived events. In Elaps, we develop a concept called impact region that allows us to identify whether a safe region is affected by newly arrived events. Moreover, we propose a novel cost model to optimize the safe region size to keep the communication overhead low. Based on the cost model, we design two incremental methods, iGM and idGM, for safe region construction. In addition, Elaps uses boolean expression, which is more expressive than keywords, to model user intent and we propose a novel index, BEQ-Tree, to handle spatial boolean expression matching. In our experiments, we use geo-tweets from Twitter and venues from Foursquare to simulate publishers and boolean expressions generated from AOL search log to represent users intentions. We test user movement in both synthetic trajectories and real taxi trajectories. The results show that Elaps can significantly reduce the communication over-head and disseminate events to users in real-time.
A Location-Aware Publish/Subscribe Framework for Parameterized Spatio-Textual Subscriptions
"... Abstract—With the rapid progress of mobile Internet and the growing popularity of smartphones, location-aware pub-lish/subscribe systems have recently attracted significant atten-tion. Different from traditional content-based publish/subscribe, subscriptions registered by subscribers and messages pu ..."
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Abstract—With the rapid progress of mobile Internet and the growing popularity of smartphones, location-aware pub-lish/subscribe systems have recently attracted significant atten-tion. Different from traditional content-based publish/subscribe, subscriptions registered by subscribers and messages published by publishers include both spatial information and textual de-scriptions, and messages should be delivered to relevant sub-scribers whose subscriptions have high relevancy to the messages. To evaluate the relevancy between spatio-textual messages and subscriptions, we should combine the spatial proximity and textual relevancy. Since subscribers have different preferences – some subscribers prefer messages with high spatial proximity and some subscribers pay more attention to messages with high textual relevancy, it calls for new location-aware publish/subscribe techniques to meet various needs from different subscribers. In this paper, we allow subscribers to parameterize their subscriptions and study the location-aware publish/subscribe problem on parameterized spatio-textual subscriptions. One big challenge is to achieve high performance. To meet this require-ment, we propose a filter-verification framework to efficiently deliver messages to relevant subscribers. In the filter step, we devise effective filters to prune large numbers of irreverent results and obtain some candidates. In the verification step, we verify the candidates to generate the answers. We propose three effective filters by integrating prefix filtering and spatial pruning tech-niques. Experimental results show our method achieves higher performance and better quality than baseline approaches. I.
Elaps: An Efficient Location-Aware Pub/Sub System
"... Abstract—The prevalence of social networks and mobile de-vices has facilitated the real-time dissemination of local events such as sales, shows and exhibitions. To explore nearby events, mobile users can query a location based search engine for the desired data. However, operating under such a pull ..."
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Abstract—The prevalence of social networks and mobile de-vices has facilitated the real-time dissemination of local events such as sales, shows and exhibitions. To explore nearby events, mobile users can query a location based search engine for the desired data. However, operating under such a pull based model means that users may miss interesting events (because no explicit queries are issued) or processing/communication overheads may be high (because users have to continuously issue queries). In this demo, we present Elaps, an efficient location-aware publish/subscribe system that can effectively disseminate inter-esting events to moving users. Elaps is based on the push model and notifies mobile users instantly whenever there is a matching event around their locations. Through the demo, we will demonstrate that Elaps is scalable to a large number of subscriptions and events. Moreover, Elaps can effectively monitor the subscribers without missing any event matching, and incur low communication overhead. I.
unknown title
"... the database group has worked on a wide range of research, ranging from traditional database tech-nology (e.g., database design, query processing and ..."
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the database group has worked on a wide range of research, ranging from traditional database tech-nology (e.g., database design, query processing and
