PODS

In this overview paper we motivate the need for and research issues arising from a new model of data processing. In this model, data does not take the form of persistent relations, but rather arrives in multiple, continuous, rapid, time-varying data ...

Research on information extraction from Web pages (wrapping) has seen much activity in recent times (particularly systems implementations), but little work has been done on formally studying the expressiveness of the formalisms proposed or on the ...

Declustering schemes allocate data blocks among multiple disks to enable parallel retrieval. Given a declustering scheme D, its response time with respect to a query Q, rt(Q), is defined to be the maximum number of disk blocks of the query stored by the ...

Modern search engines answer keyword-based queries extremely efficiently. The impressive speed is due to clever inverted index structures, caching, a domain-independent knowledge of strings, and thousands of machines. Several research efforts have ...

This paper investigates the on-line validation of streaming XML documents with respect to a DTD, under memory constraints. We first consider validation using constant memory, formalized by a finite-state automaton (FSA). We examine two flavors of the ...

XPath is a simple language for navigating an XML document and selecting a set of element nodes. XPath expressions are used to query XML data, describe key constraints, express transformations, and reference elements in remote documents. This paper ...

XSLT is the prime example of an XML query language based on tree-walking. Indeed, stripped down, XSLT is just a tree-walking tree-transducer equipped with registers and look-ahead. Motivated by this connection, we want to pinpoint the computational ...

This paper takes a first step towards the design and normalization theory for XML documents. We show that, like relational databases, XML documents may contain redundant information, and may be prone to update anomalies. Furthermore, such problems are ...

We introduce and investigate a distributed computation model for querying the Web. Web queries are computed by interacting automata running at different nodes in the Web. The automata which we are concerned with can be viewed as register automata ...

We consider the fundamental operation of applying a conjunction of selection conditions to a set of records. With large main memories available cheaply, systems may choose to keep the data entirely in main memory, in order to improve query and/or update ...

We examine the problem of efficiently computing sum/count/avg aggregates over objects with non-zero extent. Recent work on computing multi-dimensional aggregates has concentrated on objects with zero extent (points) on a multi-dimensional grid, or one-...

Users of decision support system typically submit batches of range-sum queries simultaneously rather than issuing individual, unrelated queries. We propose a wavelet based technique that exploits T/O sharing across a query batch to evaluate the set of ...

Views as a means to describe parts of a given data collection play an important role in many database applications. In dynamic environments, where data is updated, not only information provided by views, but also information provided by data sources but ...

We study two classes of view update problems in relational databases. We are given a source database S, a monotone query Q, and the view Q(S) generated by the query. The first problem that we consider is the classical view deletion problem where we wish ...

The view-selection problem is to design and materialize a set of views over a database schema, such that the choice of views minimizes the cost of evaluating the selected workload of queries, and the combined size of the materialized views does not ...

In multidimensional data models intended for online analytic processing (OLAP), data are viewed as points in a multidimensional space. Each dimension has structure, described by a directed graph of categories, a set of members for each category, and a ...

Data Warehousing and OLAP applications typically view data an having multiple logical dimensions (e.g., product, location) with natural hierarchies defined on each dimension. OLAP queries usually involve hierarchical selections on some of the dimensions,...

Database applications for moving objects pose new challenges in modeling, querying, and maintenance of objects whose locations are rapidly changing over time. Previous work on modeling and querying spatio-temporal databases and constraint databases ...

In Knowledge Compilation (KC) an intractable deduction problem KB ⊨ f is split into two phases: 1) KB is preprocessed, thus obtaining a data structure D_KB; 2) the problem is efficiently solved using D_KB and f. Our goal is to study KC in the context of ...

We consider the problem of answering queries using views, where queries and views are conjunctive queries with arithmetic comparisons (CQACs) over dense orders. Previous work only considered limited variants of this problem, without giving a complete ...

We consider conjunctive queries with arithmetic comparisons over multiple continuous data streams. We specify an algorithm for determining whether or not a query can be evaluated using a bounded amount of memory for all possible instances of the data ...

Data integration is the problem of combining data residing at different sources, and providing the user with a unified view of these data. The problem of designing data integration systems is important in current real world applications, and is ...

If the only information we have on a certain database is through a set of views, the question arises of whether this is sufficient to answer completely a given query. We say that the set of views is lossless with respect to the query, if, no matter what ...

XML specifications often consist of a type definition (typically, a DTD) and a set of integrity constraints. It has been shown previously that such specifications can be inconsistent, and thus it is often desirable to check consistency at compile-time. ...

We present algorithms to label the nodes of an XML tree which is subject to insertions and deletions of nodes. The labeling is done such that (1) we label each node immediately when it is inserted and this label remains unchanged, and (2) from a pair of ...

In this work, we study the complexity of the problem of approximate query optimization. We show that, for any δ > 0, the problem of finding a join order sequence whose cost is within a factor 2^{Θ(log1-δ(K))} of K, where K is the cost of the optimal join ...

A standard assumption in the database query optimization literature is that it suffices to optimize for the "typical" case---that is, the case in which various parameters (e.g., the amount of available memory, the selectivities of predicates, etc.) take ...