This paper describes a number of XQuery-related projects. Its goal is to show that XQuery is a useful tool for many different application scenarios. In particular, this paper tries to correct a common myth that XQuery is merely a query language and that SQL is the better query language. Instead, XQuery is a full-fledged programming language for Web applications and services. Furthermore, this paper tries to correct a second myth that XQuery is slow. This paper gives an overview of the state-of-the-art in XQuery implementation and optimization techniques and discusses one particular open-source XQuery processor, Zorba, in more detail. Among others, this paper presents an XQuery Benchmark Service which helps practitioners and XQuery processor vendors to find performance problems in an XQuery processor.
Various mechanisms, such as locking, time-stamped based algorithms, optimistic methods, versioning, have been used to support data consistency in transactions. Depending on the application's environment, InterBase offers the choices of two models for transaction handling, the consistency model, and the concurrency model. This talk presents a comprehensive overview of how Interbase's unique concurrency model, implemented with a multi-generational record structure, can improve global transaction throughput, by allowing a transaction to read a stable view of the database, without having to wait for simultaneous updates to release access to the data. A discussion of how this concurrency model handles the six classic problems of transaction management is presented Lost updates, Dirty reads, Cursor instability, Nonreproducible reads, Phantom records, Update side effects.
Over the past few years the amount of computing power and storage available to the office worker has greatly increased, resulting in the introduction of increasingly sophisticated and varied office systems applications. Many of these applications operate on structured data that could be manages by a general-purpose database system, but are instead stored in flat files in an application-specific format. On the other hand, applications that operate on relatively unstructured data, such as for word processing, need the transparency and efficiency of a conventional file interface.To this end, we have developed the "Office Database" (ODB), an integrated database and file system based on the Entity_Relationship model. The ODB database interface supports structured data, while the file system interface supports the unstructured data. ODB databases also serve as directories for files (and databases, allowing arbitrary organization and identification of user files and databases.This paper first describes the office application environment and the requirements for an office database. Next, the data model and programming interface for ODB are described. Following this is a description of a full-screen interactive interface to ODB. An overview of the implementation of ODB is given, as well as some details on the current status, and conclusions about the significance of the work.
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