SIGMOD

In the mobile wireless computing environment of the future a large number of users equipped with low powered palm-top machines will query databases over the wireless communication channels. Palmtop based units will often be disconnected for prolonged ...

Users of mobile computers will soon have online access to a large number of databases via wireless networks. Because of limited bandwidth, wireless communication is more expensive than wire communication. In this paper we present and analyze various ...

We consider wireless broadcasting of data as a way of disseminating information to a massive number of users. Organizing and accessing information on wireless communication channels is different from the problem of organizing and accessing data on the ...

Various types of computer systems are used behind the scenes in many parts of the telecommunications network to ensure its efficient and trouble-free operation. These systems are large, complex, and expensive real-time computer systems that are mission ...

Extended transaction models in databases were motivated by the needs of complex applications such as CAD and software engineering. Transactions in such applications have diverse needs, for example, they may be long lived and they may need to cooperate. ...

This paper presents an algorithm, called ARIES/CSA (Algorithm for Recovery and Isolation Exploiting Semantics for Client-Server Architectures), for performing recovery correctly in client-server (CS) architectures. In CS, the server manages the disk ...

Global transaction management requires cooperation from local sites to ensure the consistent and reliable execution of global transactions in a distributed database system. In a heterogeneous distributed database (or multidatabase) environment, various ...

Multimedia information systems have emerged as an essential component of many application domains ranging from library information systems to entertainment technology. However, most implementations of these systems cannot support the continuous display ...

Many aspects of time-based media—complex data encoding, compression, “quality factors,” timing—appear problematic from a data modeling standpoint. This paper proposes timed streams as the basic abstraction for modeling time-based media. Several media-...

We describe the implementation of the magic-sets transformation in the Starburst extensible relational database system. To our knowledge this is the first implementation of the magic-sets transformation in a relational database system. The Starburst ...

Suppose you are given a set of natural entities (e.g., proteins, organisms, weather patterns, etc.) that possess some important common externally observable properties. You also have a structural description of the entities (e.g., sequence, topological, ...

The popularity of on-line document databases has led to a new problem: finding which text databases (out of many candidate choices) are the most relevant to a user. Identifying the relevant databases for a given query is the text database discovery ...

When we, humans, talk to each other we have no trouble disambiguating what another person means, although our statements are almost never meticulously specified down to very last detail. We “fill in the gaps” using our common-sense knowledge about the ...

Traditional query optimizers assume accurate knowledge of run-time parameters such as selectivities and resource availability during plan optimization, i.e., at compile time. In reality, however, this assumption is often not justified. Therefore, the “...

In this paper, we propose a novel approach for estimating the record selectivities of database queries. The real attribute value distribution is adaptively approximated by a curve-fitting function using a query feedback mechanism. This approach has the ...

We describe an algorithm for estimating the number of page fetches for a partial or complete scan of a B-tree index. The algorithm obtains estimates for the number of page fetches for an index scan when given the number of tuples selected and the number ...

In this paper we study parallel execution of multiple pipelined hash joins. Specifically, we deal with two issues, processor allocation and the use of hash filters, to improve parallel execution of hash joins. We first present a scheme to transform a ...

Spatial joins are one of the most important operations for combining spatial objects of several relations. In this paper, spatial join processing is studied in detail for extended spatial objects in two-dimensional data space. We present an approach for ...

Existing methods for spatial joins assume the existence of indices for the participating data sets. This assumption is not realistic for applications involving multiple map layer overlays or for queries involving non-spatial selections. In this paper, ...

The demanding performance objectives that real-time database systems (RTDBS) face necessitate the use of priority resource scheduling. This paper introduces a Priority Memory Management (PMM) algorithm that is designed to schedule queries in RTDBS. PMM ...

A new sort algorithm, called AlphaSort, demonstrates that commodity processors and disks can handle commercial batch workloads. Using Alpha AXP processors, commodity memory, and arrays of SCSI disks, AlphaSort runs the industry-standard sort benchmark ...

Evaluating database system performance often requires generating synthetic databases—ones having certain statistical properties but filled with dummy information. When evaluating different database designs, it is often necessary to generate several ...

This paper presents a distributed file organization for record-structured, disk-resident files with key-based exact-match access. The file is organized into buckets that are spread across multiple servers, where a server may hold multiple buckets. ...

Databases are growing steadily, and distributed computer systems are more and more easily available. This provides an opportunity to satisfy the increasingly tighter efficiency requirements by means of distributed data structures. The design and ...

Expert Databases are environments that support the processing of rule programs against a disk resident database. They occupy a position intermediate between active and deductive databases, with respect to the level of abstraction of the underlying rule ...

With the proliferation of the world's “information highways” a renewed interest in efficient document indexing techniques has come about. In this paper, the problem of incremental updates of inverted lists is addressed using a new dual-structure index. ...

We present a framework which allows the user to access and manipulate data uniformly, regardless of whether it resides in a database or in the file system (or in both). A key issue is the performance of the system. We show that text indexing, combined ...

Structured documents (e.g., SGML) can benefit a lot from database support and more specifically from object-oriented database (OODB) management systems. This paper describes a natural mapping from SGML documents into OODB's and a formal extension of two ...

Recent work in query optimization has addressed the issue of placing expensive predicates in a query plan. In this paper we explore the predicate placement options considered in the Montage DBMS, presenting a family of algorithms that form successively ...

In this work, we propose and assess a technique called bypass processing for optimizing the evaluation of disjunctive queries with expensive predicates. The technique is particularly useful for optimizing selection predicates that contain terms whose ...