Journal articleProceedings of the ACM on Management of Data · May 12, 2026
Query optimizers must efficiently choose a query plan using noisy estimates of cardinalities. We study robust query optimization, where the optimizer is made aware of the uncertainty in cardinality estimates and needs to select the most ''robust'' ...
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Journal articleProceedings of the ACM on Management of Data · April 2, 2026
Embedding-based dense retrieval has become the cornerstone of many critical applications, where approximate nearest neighbor search (ANNS) queries are often combined with filters on labels such as dates and price ranges. Graph-based indexes achieve ...
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Journal articleProceedings of the ACM on Management of Data · November 4, 2024
Data summarization is a powerful approach to deal with large-scale data analytics, which has wide applications in web search, recommendation systems, approximate query processing, etc. It computes a small, compact summary that preserve ...
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Journal articleAnnals of the Entomological Society of America · May 29, 2024
We describe a system called Qr-Hint that, given a (correct) target query Q* and a (wrong) working query Q, both expressed in SQL, provides actionable hints for the user to fix the working query so that it becomes semantically equivalent to the t ...
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Journal articleProceedings of the ACM on Management of Data · May 10, 2024
Finding patterns in graphs is a fundamental problem in databases and data mining. In many applications, graphs are temporal and evolve over time, so we are interested in finding durable patterns, such as triangles and paths, which persist over a lo ...
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Journal articleVaccine · April 2024
We present VaxConcerns, a taxonomy for vaccine concerns and misinformation. VaxConcerns is an easy-to-teach taxonomy of concerns and misinformation commonly found among online anti-vaccination media and is evaluated to produce high-quality data annotations ...
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Journal articleLeibniz International Proceedings in Informatics Lipics · July 1, 2021
This paper considers enumerating answers to similarity-join queries under dynamic updates: Given two sets of n points A,B in ℝd, a metric φ(·), and a distance threshold r > 0, report all pairs of points (a, b) ∈ A × B with φ(a, b) ≤ r. Our goal is to store ...
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Journal articleProceedings International Conference on Data Engineering · April 1, 2021
A way of finding interesting or exceptional records from instant-stamped temporal data is to consider their "durability, "or, intuitively speaking, how well they compare with other records that arrived earlier or later, and how long they retain their supre ...
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Journal articleProceedings of the ACM SIGMOD International Conference on Management of Data · January 1, 2021
We consider a class of queries called durability prediction queries that arise commonly in predictive analytics, where we use a given predictive model to answer questions about possible futures to inform our decisions. Examples of durability prediction que ...
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Journal articleProceedings of the VLDB Endowment · January 1, 2020
We study the optimization problem of selecting numerical quantities to clean in order to fact-check claims based on such data. Oftentimes, such claims are technically correct, but they can still mislead for two reasons. First, data may contain uncertainty ...
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Journal articleProceedings of the VLDB Endowment · January 1, 2020
We demonstrate I-REX1, a system designed to help users understand SQL query evaluation and debug SQL queries. I-REX lets users interactively “trace” the evaluation of complex SQL queries, including those with correlated subqueries. I-REX also ex ...
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Journal articleProceedings. ACM-SIGMOD International Conference on Management of Data · June 2019
For testing the correctness of SQL queries, e.g., evaluating student submissions in a database course, a standard practice is to execute the query in question on some test database instance and compare its result with that of the correct query. Given two q ...
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Journal articleProceedings of the ... ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems. ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems · June 2018
We investigate the complexity of computing an optimal repair of an inconsistent database, in the case where integrity constraints are Functional Dependencies (FDs). We focus on two types of repairs: an optimal subset repair (optimal S-repair) that is obtai ...
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Journal articleProceedings of the VLDB Endowment · January 1, 2018
Estimation of the accuracy of a large-scale knowledge graph (KG) often requires humans to annotate samples from the graph. How to obtain statistically meaningful estimates for accuracy evaluation while keeping human annotation costs low is a problem critic ...
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Journal articleACM Transactions on Database Systems · January 1, 2017
Our media is saturated with claims of "facts" made from data. Database research has in the past focused on how to answer queries, but has not devotedmuch attention to discerningmore subtle qualities of the resulting claims, for example, is a claim "cherry- ...
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Journal articleIEEE Transactions on Knowledge and Data Engineering · February 1, 2016
Given a set of objects O, each with d numeric attributes, a top-k preference scores these objects using a linear combination of their attribute values, where the weight on each attribute reflects the interest in this attribute. Given a query preference q, ...
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Journal articleLecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics · January 1, 2015Cite
Journal articleProceedings of the VLDB Endowment · January 1, 2014
Our news are saturated with claims of "facts" made from data.Database research has in the past focused on how to answer queries,but has not devoted much attention to discerning more subtle qualities of the resulting claims, e.g., is a claim "cherry-picking ...
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Journal articleProceedings International Conference on Data Engineering · January 1, 2014
Given a set of objects O, each with d numeric attributes, a top-k preference scores these objects using a linear combination of their attribute values, where the weight on each attribute reflects the interest in this attribute. Given a query preference q, ...
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Journal articleProceedings International Conference on Data Engineering · January 1, 2014
We study the novel problem of finding new, prominent situational facts, which are emerging statements about objects that stand out within certain contexts. Many such facts are newsworthy - e.g., an athlete's outstanding performance in a game, or a viral vi ...
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Journal articleProceedings of the ACM SIGMOD International Conference on Management of Data · January 1, 2014
Are you fed up with "lies, d - ned lies, and statistics" made up from data in our media? For claims based on structured data, we present a system to automatically assess the quality of claims (beyond their correctness) and counter misleading claims that ch ...
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Journal articleProceedings of the VLDB Endowment · January 1, 2014
Towards computational journalism, we present FactWatcher, a system that helps journalists identify data-backed, attention-seizing facts which serve as leads to news stories. FactWatcher discovers three types of facts, including situational facts, one-of-th ...
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Journal articleProceedings of the ACM SIGMOD International Conference on Management of Data · July 29, 2013
We present Cumulon, a system designed to help users rapidly develop and intelligently deploy matrix-based big-data analysis programs in the cloud. Cumulon features a flexible execution model and new operators especially suited for such workloads. We show h ...
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Journal articleIEEE Transactions on Knowledge and Data Engineering · April 8, 2013
Wireless sensor networks are widely used to continuously collect data from the environment. Because of energy constraints on battery-powered nodes, it is critical to minimize communication. Suppression has been proposed as a way to reduce communication by ...
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Journal articleComputational Geometry Theory and Applications · April 1, 2013
We present external memory data structures for efficiently answering range-aggregate queries. The range-aggregate problem is defined as follows: Given a set of weighted points in Rd, compute the aggregate of the weights of the points that lie in ...
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Journal articleProceedings of the VLDB Endowment · January 1, 2013
Permutation is a fundamental operator for array data, with applications in, for example, changing matrix layouts and reorganizing data cubes. We consider the problem of permuting large quantities of data stored on secondary storage that supports fast rando ...
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Journal articleACM International Conference Proceeding Series · December 19, 2012
Solid-state drives are becoming a viable alternative to magnetic disks in database systems, but their performance characteristics, particularly those caused by their erase-before-write behavior, make conventional database indexes a poor fit. There have bee ...
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Journal articleProceedings of the ACM SIGKDD International Conference on Knowledge Discovery and Data Mining · September 14, 2012
Objects with multiple numeric attributes can be compared within any "subspace" (subset of attributes). In applications such as computational journalism, users are interested in claims of the form: Karl Malone is one of the only two players in NBA history w ...
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Journal articleIEEE Transactions on Knowledge and Data Engineering · August 29, 2012
We study the problem of assigning subscribers to brokers in a wide-area content-based publish/subscribe system. A good assignment should consider both subscriber interests in the event space and subscriber locations in the network space, and balance multip ...
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Journal articleProceedings International Conference on Data Engineering · July 30, 2012
We consider how to support a large number of users over a wide-area network whose interests are characterised by range top-k continuous queries. Given an object update, we need to notify users whose top-k results are affected. Simple solutions include usin ...
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Journal articleProceedings of the ACM SIGMOD International Conference on Management of Data · June 28, 2012
Given a set of objects, each with multiple numeric attributes, a (preference) top-k query retrieves the k objects with the highest scores according to a user preference, defined as a linear combination of attribute values. We consider the problem of proces ...
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Journal articleProceedings of the VLDB Endowment · January 1, 2012
Big array analytics is becoming indispensable in answering important scientific and business questions. Most analysis tasks consist of multiple steps, each making one or multiple passes over the arrays to be analyzed and generating intermediate results. In ...
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Journal articleFoundations and Trends in Databases · December 1, 2011
Materialized views are queries whose results are stored and maintained in order to facilitate access to data in their underlying base tables. In the SQL setting, they are now considered a mature technology implemented by most commercial database systems an ...
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Journal articleEcological applications : a publication of the Ecological Society of America · July 2011
Recent developments suggest that predictive modeling could begin to play a larger role not only for data analysis, but also for data collection. We address the example of efficient wireless sensor networks, where inferential ecosystem models can be used to ...
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Journal articleProceedings International Conference on Data Engineering · June 6, 2011
We study the problem of assigning subscribers to brokers in a wide-area content-based publish/subscribe system. A good assignment should consider both subscriber interests in the event space and subscriber locations in the network space, and balance multip ...
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Journal articleLecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics · August 3, 2010Cite
Journal articleProceedings International Conference on Data Engineering · June 1, 2010
Statistical analysis of massive data is becoming indispensable to science, commerce, and society today. Such analysis requires efficient, flexible storage support and special optimization techniques. In this demo, we present RIOT (R with I/O Transparency), ...
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Journal articleSIGMOD Pods 09 Proceedings of the International Conference on Management of Data and 28th Symposium on Principles of Database Systems · December 4, 2009
Most information extraction (IE) approaches have considered only static text corpora, over which we apply IE only once. Many real-world text corpora however are dynamic. They evolve over time, and so to keep extracted information up to date we often must a ...
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Journal articleACM Transactions on Database Systems · August 1, 2009
This article considers the problem of scalably processing a large number of continuous queries. Our approach, consisting of novel data structures and algorithms and a flexible processing framework, advances the state-of-the-art in several ways. First, our ...
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Journal articleLecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics · July 15, 2009Cite
Journal articleProceedings International Conference on Data Engineering · July 8, 2009
We consider the problem of efficiently computing weighted proximity best-joins over multiple lists, with applications in information retrieval and extraction. We are given a multi-term query, and for each query term, a list of all its matches with scores, ...
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Journal articleCidr 2009 4th Biennal Conference on Innovative Data Systems Research · January 1, 2009
R is a numerical computing environment that is widely popular for statistical data analysis. Like many such environments, R performs poorly for large datasets whose sizes exceed that of physical memory. We present our vision of RIOT (R with I/O Transparenc ...
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Journal articleProceedings of the ACM SIGMOD International Conference on Management of Data · December 10, 2008
We demonstrate ProSem, a scalable wide-area publish/subscribe system that supports complex, stateful subscriptions as well as simple ones. One unique feature of ProSem is its cost-based joint optimization of both subscription processing and notification di ...
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Journal article5th International Workshop on Data Management for Sensor Networks Dmsn 08 in Conjunction with the 34th International Conference on Very Large Data Bases · December 1, 2008Cite
Journal articleProceedings International Conference on Data Engineering · October 1, 2008
There has been a recent resurgence of interest in research on noisy and incomplete data. Many applications require information to be recovered from such data. Ideally, an approach for information recovery should have the following features. First, it shoul ...
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Journal articleProceedings International Conference on Data Engineering · October 1, 2008
Most current information extraction (IE) approaches have considered only static text corpora, over which we typically have to apply IE only once. Many real-world text corpora however are dynamic. They evolve over time, and to keep extracted information up ...
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Journal articleProceedings of the VLDB Endowment · January 1, 2008
We address the problem of supporting a large number of select-join subscriptions for wide-area publish/subscribe. Subscriptions are joins over different tables, with varying interests expressed as range selection conditions over table attributes. Naive sch ...
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Journal articleSIGMOD Record · December 1, 2007
A report on the Fourth International Workshop on Data Management for Sensor Networks (DMSN), which was held on September 24, 2007, is presented. The topics presented include a keystone address, three research sessions, panel discussion on the present and t ...
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Journal articleProceedings of the ACM SIGMOD International Conference on Management of Data · October 30, 2007
Suppose a long-running analytical query is executing on a database server and has been allocated a large amount of physical memory. A high-priority task comes in and we need to run it immediately with all available resources. We have several choices. We co ...
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Journal articleProceedings of the ACM SIGMOD International Conference on Management of Data · October 30, 2007
Query processing over graph-structured data is enjoying a growing number of applications. A top-k keyword search query on a graph finds the top k answers according to some ranking criteria, where each answer is a substructure of the graph containing all qu ...
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Journal articleProceedings International Conference on Data Engineering · September 24, 2007
Wireless sensor networks have enormous potential to aid data collection in a number of areas, such as environmental and wildlife research. In this paper, we address the challenges of supporting many-to-many aggregation in a sensor network. An application o ...
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Journal articleProceedings of the ACM SIGMOD International Conference on Management of Data · December 1, 2006
Monitoring extreme values (MAX or MIN) is a fundamental problem in wireless sensor networks (and in general, complex dynamic systems). This problem presents very different algorithmic challenges from aggregate and selection queries, in the sense that an in ...
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Journal articleProceedings of the ACM SIGMOD International Conference on Management of Data · December 1, 2006
Wireless sensor networks have created new opportunities for data collection in a variety of scenarios, such as environmental and industrial, where we expect data to be temporally and spatially correlated. Researchers may want to continuously collect all se ...
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Journal articleProceedings of the ACM SIGMOD International Conference on Management of Data · December 1, 2006
The work performed by a publish/subscribe system can conceptually be divided into subscription processing and notification dissemination. Traditionally, research in the database and networking communities has focused on these aspects in isolation. The inte ...
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Journal articleProceedings International Conference on Data Engineering · October 17, 2006
Wireless sensor networks generate a vast amount of data. This data, however, must be sparingly extracted to conserve energy, usually the most precious resource in battery-powered sensors. When approximation is acceptable, a model-driven approach to query p ...
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Journal articleProceedings International Conference on Data Engineering · October 17, 2006
Graph reachability is fundamental to a wide range of applications, including XML indexing, geographic navigation, Internet routing, ontology queries based on RDF/OWL, etc. Many applications involve huge graphs and require fast answering of reachability que ...
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Journal articleProceedings International Conference on Data Engineering · October 17, 2006
Environmental monitoring is a promising application for sensor networks. Many scenarios produce geographically correlated readings, making them visually interesting and good targets for the isoline query. This query depicts boundaries showing how values ch ...
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Journal articleLecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics · July 7, 2006
As networks continue to grow in size and complexity, distributed network monitoring and resource querying are becoming increasingly difficult. Our aim is to design, build, and evaluate a scalable infrastructure for answering queries over distributed measur ...
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Journal articleLecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics · January 1, 2006
Next-generation wireless sensor networks may revolutionize understanding of environmental change by assimilating heterogeneous data, assessing the relative value and costs of data collection, and scheduling activities accordingly. Thus, they are dynamic, d ...
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Journal articleProceedings International Conference on Data Engineering · December 12, 2005
Incremental view maintenance has found a growing number of applications recently, including data warehousing, continuous query processing, publish/subscribe systems, etc. Batch processing of base table modifications, when applicable, can be much more effic ...
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Journal articleProceedings International Conference on Data Engineering · December 12, 2005
Order-based element labeling for tree-structured XML data is an important technique in XML processing. It lies at the core of many fundamental XML operations such as containment join and twig matching. While labeling for static XML documents is well unders ...
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Journal articleLecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics · December 1, 2005
A continuous query is a standing query over a dynamic data set whose query result needs to be constantly updated as new data arrive. We consider the problem of constructing a data structure on a set of continuous band-join queries over two data sets R and ...
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Journal articleProceedings of the ACM SIGMOD International Conference on Management of Data · December 1, 2005
We consider the problem of joining data streams using limited cache memory, with the goal of producing as many result tuples as possible from the cache. Many cache replacement heuristics have been proposed in the past. Their performance often relies on imp ...
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Journal articleLecture Notes in Computer Science · January 1, 2005
A materialized view is a certain synopsis structure precomputed from one or more data sets (called base tables) in order to facilitate various queries on the data. When the underlying base tables change, the materialized view also needs to be updated accor ...
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Journal articleInternational Conference on Information and Knowledge Management Proceedings · January 1, 2005
Testing reachability between nodes in a graph is a well-known problem with many important applications, including knowledge representation, program analysis, and more recently, biological and ontology databases inferencing as well as XML query processing. ...
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Journal articleProceedings of the International Database Engineering and Applications Symposium Ideas · October 25, 2004
The Web has greatly facilitated access to information. However, information presented in HTML is mainly intended to be browsed by humans, and the problem of automatically extracting such information remains an important and challenging task. In this work, ...
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Journal articleProceedings International Conference on Data Engineering · June 1, 2004
XML and other types of semi-structured data are typically represented by a labeled directed graph. To speed up path expression queries over the graph, a variety of structural indexes have been proposed. They usually work by partitioning nodes in the data g ...
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Journal articleProceedings International Conference on Data Engineering · June 1, 2004
XML plays an important role in delivering data over the Internet, and the need to store and manipulate XML in its native format has become increasingly relevant. This growing need necessitates work on developing native XML operators, especially for one as ...
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Journal articleProceedings of the ACM SIGMOD International Conference on Management of Data · January 1, 2004
Increasing popularity of XML in recent years has generated much interest in query processing over graph-structured data. To support officient evaluation of path expressions, many structural indexes have been proposed. The most popular ones are the 1-index, ...
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Journal articleProceedings International Conference on Data Engineering · December 2, 2003
We tackle the problem of maintaining materialized top-k views in this paper. Top-k queries, including MIN and MAX as important special cases, occur frequently in common database workloads. A top-k view can be materialized to improve query performance, but ...
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Journal articleVLDB Journal · October 1, 2003
We consider the problems of computing aggregation queries in temporal databases and of maintaining materialized temporal aggregate views efficiently. The latter problem is particularly challenging since a single data update can cause aggregate results to c ...
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Journal articleLecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics · January 1, 2003
We develop several linear or near-linear space and I/O-efficient dynamic data structures for orthogonal range-max queries and stabbing-max queries. Given a set of N weighted points in ℝd, the range-max problem asks for the maximum-weight point i ...
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Journal articleJournal of Computer Science and Technology · January 1, 2003
The study on database technologies, or more generally, the technologies of data and information management, is an important and active research field. Recently, many exciting results have been reported. In this fast growing field, Chinese researchers play ...
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Journal articleLecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics · January 1, 2003
Google's successful PageRank brings to the Web an order that well reflects the relative importance of Web pages. Inspired by PageRank, we propose a similar scheme called TupleRank for ranking tuples in a relational database. Database tuples naturally relat ...
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Journal articleProceedings International Conference on Data Engineering · January 1, 2001
We consider the problems of computing aggregation queries in temporal databases, and of maintaining materialized temporal aggregate views efficiently. The latter problem is particularly challenging since a single data update can cause aggregate results to ...
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Journal articleLecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics · January 1, 2000
View self-maintenance refers to maintaining materialized views without accessing base data. Self-maintenance is particularly useful in data warehousing settings, where base data comes from sources that may be inaccessible. Self-maintenance has been studied ...
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Journal articleSIGMOD Record · January 1, 2000
Commercial relational database systems today provide only limited temporal support. To address the needs of applications requiring rich temporal data and queries, we have built TIP (Temporal Information Processor), a temporal extension to the Informix data ...
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Journal articleLecture Notes in Computer Science Including Subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics · January 1, 1998
An important use of data warehousing is to provide temporal views over the history of source data that may itself be non-temporal. While recent work in view maintenance is applicable to data warehousing, only non-temporal views have been considered. In thi ...
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