Proceedings 17th International Conference on Data Engineering

A wide-area distributed message delivery system can use replication to improve performance and availability. However, without safeguards, replicated messages may be delivered to a mobile device more than once, making the device's user repeat actions (e.g. making unnecessary phone calls, firing weapons repeatedly). Alternatively, they may not be delivered at all, making the user miss important mess... View full abstract»

Presents READY, a multi-threaded implementation of the CORBA Notification Service. The main contribution of our work is the design and development of scalable solutions for the implementation of the CORBA Notification Service. In particular, we present the overall architecture of READY, discuss the key design challenges and choices we made with respect to filter evaluation and event dispatching, a... View full abstract»

High availability for both data and applications is rapidly becoming a business requirement. While database systems support recovery, providing high database availability, applications may still lose work because of server outages. When a server crashes, any volatile state associated with the application's database session is lost and the application may require an operator-assisted restart. This ... View full abstract»

There have been many temporal data models proposed in the literature. Most of them are based on relational models. Despite their popularity as design and analysis tools for information systems, entity-relationship (ER) based temporal data models have not drawn as much attention as those based on relational models. One reason is that most ER-based temporal data models lack an underlying formalism a... View full abstract»

The timestamps of now-relative bitemporal databases are modeled as growing, shrinking or rectangular regions. The shape of these regions makes it a challenge to design bitemporal operators that (a) are consistent with the point-based interpretation of a temporal database, (b) preserve the identity of the argument timestamps, (c) ensure locality and (d) perform efficiently. We identify the bitempor... View full abstract»

Considers 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 change over the entire time-line. We introduce a new index structure called the SB-tree, which incorporates features from both segment trees (S-tr... View full abstract»

Over the last decade, database system products have been extended to provide support for defining, storing, updating, indexing and retrieving complex data with full transaction semantics. Oracle, IBM, Informix and others have used extensibility technology to build database system extensions for text, image, spatial, audio/video, chemical, genetic and other types of complex data. Currently, we find... View full abstract»

Supply-chain management is a crucial activity in every company. Surprisingly, today, most of the supply-chain activities are carried out manually, and IT support is often limited to having a set of (disconnected) data repositories. In addition, business-to-business (B2B) communications are performed via phone, fax or e-mail. Increasing the operational efficiency of the supply chain results in huge... View full abstract»

Proposes an extension to current view-based mediator systems called "model-based mediation", in which views are defined and executed at the level of conceptual models (CMs) rather than at the structural level. Structural integration and lifting of data to the conceptual level is "pushed down" from the mediator to wrappers which, in our system, export the classes, associations, constraints and quer... View full abstract»

LeSelect is a mediator system which allows scientists to publish their resources (data and programs) so they can be transparently accessed. The scientists can typically issue queries which access distributed published data and involve the execution of expensive functions (corresponding to programs). Furthermore, the queries can involve large objects, such as images (e.g. archived meteorological sa... View full abstract»

The management of product-related data in a uniform and consistent way is a big challenge for many manufacturing enterprises, especially the large ones, like DaimlerChrysler. So-called product data management (PDM) systems are a promising way to achieve this goal. For various reasons, PDM systems often sit on top of a relational DBMS, using it (more or less) as a simple record manager. User intera... View full abstract»

What do you do to make sense of a mass of information on a given topic? Paradoxically, you likely add yet more information to the pile: annotations, underlining, bookmarks, cross-references, etc. We want to build digital information systems for managing such added or superimposed information and support applications that create and manipulate it. We find that requirements for a superimposed inform... View full abstract»

Our concern is the design of a scalable infrastructure for complex application services. We want to find out if a cluster of commodity database systems is well-suited as such an infrastructure. To this end, we have carried out a feasibility study based on document services, e.g. document insertion and retrieval. We decompose a service request into short parallel database transactions. Our system, ... View full abstract»

Primary key and referential integrity are the most widely used integrity constraints in relational databases. Each has a sequenced analogue in temporal databases, in which the constraint must apply independently at every point in time. In this paper, we assume a stratum approach, which expresses the checking in conventional SQL, as triggers on period-stamped relations. We evaluate several novel ap... View full abstract»

XML is increasingly gaining acceptance as a medium for exchanging data between applications. Given its text-based structure, XML can easily be distributed across any type of communication channel, including the Internet. This article provides an overview of an efficient way to store XML data inside an object-oriented database management system (OODBMS). It first discusses the difference between XM... View full abstract»

For better or for worse, XML has emerged as a de facto standard for data interchange. This consensus is likely to lead to increased demand for technology that allows users to integrate data from a variety of applications, repositories, and partners, which are located across the corporate intranet or on the Internet. Nimble Technology has spent two years developing a product to service this market.... View full abstract»

Studies the impact of several lock manager designs on the overhead imposed on a persistent programming language by automated object locking. Our study reveals that a lock management method based on lock-state sharing outperforms more traditional lock management designs. Lock-state sharing is a novel lock management method that represents all lock data structures with equal values with a single sha... View full abstract»

With a GByte of memory priced at less than $2000, main-memory DBMSs (MMDBMSs) are emerging as an economically viable alternative to disk-resident DBMSs (DRDBMSs) in many problem domains. The MMDBMS can show significantly higher performance than the DRDBMS by reducing disk accesses to the sequential form of log writing and occasional checkpointing. Upon a system crash, the recovery process begins b... View full abstract»

Many applications require that large amounts of data are deleted from a database - typically, such bulk deletes are carried out periodically and involve old or out-of-date data. If the data is not partitioned in such a way that bulk deletes can be carried out by simply deleting whole partitions, then most current database products execute such bulk delete operations very poorly. The reason is that... View full abstract»

Previous work on frequent item set mining has focused on finding all itemsets that are frequent in a specified part of a database. We motivate the dual question of finding under what circumstances a given item set satisfies a pattern of interest (e.g., frequency) in a database. Circumstances form a lattice that generalizes the instance lattice associated with datacube. Exploiting this, we adapt kn... View full abstract»

Periodic behavior is common in real-world applications. However in many cases, periodicities are partial in that they are present only intermittently. The authors study such intermittent patterns, which they refer to as p-patterns. The formulation of p-patterns takes into account imprecise time information (e.g., due to unsynchronized clocks in distributed environments), noisy data (e.g., due to e... View full abstract»

Applications require access to database servers for many purposes. Mobile users, those who use their computing devices away from a traditional local area network, require access to data even when central database servers are unavailable. iAnywhere Solutions provides a number of solutions that address the challenges of offline and wireless data access. The article discusses those challenges and pre... View full abstract»