VLDB

The traditional view of distributed databases is based on a number of database servers with regular communication. Today information is stored not only in these central databases, but on a myriad of computers and computer-based devices in addition to ...

At a fundamental level, the key challenge in data integration is to reconcile the semantics of disparate data sets, each expressed with a different database structure. I argue that computing statistics over a large number of structures offers a powerful ...

The last decade has witnessed tremendous advances in data mining. We take a retrospective look at these developments, focusing on association rules discovery, and discuss the challenges and opportunities ahead.

Large boolean matrices are a basic representational unit in a variety of applications, with some notable examples being interactive visualization systems, mining large graph structures, and association rule mining. Designing space and time efficient ...

It is well established that bitmap indices are efficient for read-only attributes with low attribute cardinalities. For an attribute with a high cardinality, the size of the bitmap index can be very large. To overcome this size problem, specialized ...

Large string datasets are common in a number of emerging text and biological database applications. Common queries over such datasets include both exact and approximate string matches. These queries can be evaluated very efficiently by using a suffix ...

When a client submits a set of XPath queries to a XML database on a network, the set of answer sets sent back by the database may include redundancy in two ways: some elements may appear in more than one answer set, and some elements in some answer sets ...

XML languages, such as XQuery, XSLT and SQL/XML, employ XPath as the search and extraction language. XPath expressions often define complicated navigation, resulting in expensive query processing, especially when executed over large collections of ...

The widespread adoption of XML holds out the promise that document structure can be exploited to specify precise database queries. However, the user may have only a limited knowledge of the XML structure, and hence may be unable to produce a correct ...

The erosion of trust put in traditional database servers and in Database Service Providers, the growing interest for different forms of data dissemination and the concern for protecting children from suspicious Internet content are different factors ...

Recent applications are seeing an increasing need that publishing XML documents should meet precise security requirements. In this paper, we consider data-publishing applications where the publisher specifies what information is sensitive and should be ...

We present a practical and efficient approach to incorporating privacy policy enforcement into an existing application and database environment, and we explore some of the semantic tradeoffs introduced by enforcing these privacy policy rules at cell-...

XPath and XQuery (which includes XPath as a sublanguage) are the major query languages for XML. An important issue arising in efficient evaluation of queries expressed in these languages is satisfiability, i.e., whether there exists a database, ...

Query containment is the most fundamental relationship between a pair of database queries: a query Q is said to be contained in a query Q′ if the answer for Q is always a subset of the answer for Q′, independent of the current state of the database. ...

We consider the efficiency of queries generated by XML to SQL translation. We first show that published XML-to-SQL query translation algorithms are suboptimal in that they often translate simple path expressions into complex SQL queries even when much ...

This paper presents a novel and complementary technique to optimize an XPath query by minimizing its wildcard steps. Our approach is based on using a general composite axis called the layer axis, to rewrite a sequence of XPath steps (all of which are ...

Classical logical optimization techniques rely on a logical semantics of the query language. The adaptation of these techniques to XQuery is precluded by its definition as a functional language with operational semantics. We introduce Nested XML ...

Detecting changes in a data stream is an important area of research with many applications. In this paper, we present a novel method for the detection and estimation of change. In addition to providing statistical guarantees on the reliability of ...

We introduce the notion of stochastic consistency, and propose a novel approach to achieving it for caches of highly erratic data. Erratic data sources, such as stock prices, sensor data, are common and important in practice. However, their erratic ...

The problem of finding frequent items has been recently studied over high speed data streams. However, mining frequent itemsets from transactional data streams has not been well addressed yet in terms of its bounds of memory consumption. The main ...

Different models have been proposed recently for representing temporal data, tracking historical information, and recovering the state of the document as of any given time, in XML documents. We address the problem of indexing temporal XML documents. In ...

We introduce an extension of the XQuery language, FluX, that supports event-based query processing and the conscious handling of main memory buffers. Purely event-based queries of this language can be executed on streaming XML data in a very direct way. ...

Cost-based XML query optimization calls for accurate estimation of the selectivity of path expressions. Some other interactive and internet applications can also benefit from such estimations. While there are a number of estimation techniques proposed ...

Relational database systems may be turned into efficient XML and XPath processors if the system is provided with a suitable relational tree encoding. This paper extends this relational XML processing stack and shows that an RDBMS can also serve as a ...

An increasing percentage of the data needed by business applications is being generated in XML format. Storing the XML in its native format will facilitate new applications that exchange business objects in XML format and query portions of XML documents ...

This paper addresses the question of updating relational databases through XML views. Using query trees to capture the notions of selection, projection, nesting, grouping, and heterogeneous sets found throughout most XML query languages, we show how XML ...

Wavelet synopses have been found to be of interest in query optimization and approximate query answering. Recently, extended wavelets were proposed by Deligiannakis and Roussopoulos for data sets containing multiple measures. Extended wavelets optimize ...

Histograms and Wavelet synopses provide useful tools in query optimization and approximate query answering. Traditional histogram construction algorithms, such as V-Optimal, optimize absolute error measures for which the error in estimating a true value ...

We consider the problem of estimating set-expression cardinality in a distributed streaming environment where rapid update streams originating at remote sites are continually transmitted to a central processing system. At the core of our algorithmic ...

We address the problem of computing approximate answers to continuous sliding-window joins over data streams when the available memory may be insufficient to keep the entire join state. One approximation scenario is to provide a maximum subset of the ...