MOD

Recently we have proposed an adaptive, random sampling algorithm for general query size estimation. In earlier work we analyzed the asymptotic efficiency and accuracy of the algorithm, in this paper we investigate its practicality as applied to selects ...

Most existing databases lack features which allow for the convenient manipulation of text. It is even more difficult to use them if the text language is not based on the Roman alphabet. The Arabic language is a very good example of this case. Many ...

OdeView is the graphical front end for Ode, an object-oriented database system and environment. Ode's data model supports data encapsulation, type inheritance, and complex objects. OdeView provides facilities for examining the database schema (i.e., the ...

Suppose a directed graph has its arcs stored in secondary memory, and we wish to compute its transitive closure, also storing the result in secondary memory. We assume that an amount of main memory capable of holding s “values” is available, and that s ...

The expressive power of pure deductive database languages, such as DATALOG and stratified DATALOGS, is limited in a sense that some useful queries such as functions involving aggregation are not definable in these languages. Our concern in this paper is ...

A number of optimizations have been proposed for Datalog programs involving a single intensional predicate (“single-IDB programs”). Examples include the detection of commutativity and separability ([Naug88],[RSUV89], [Ioan89a]) in linear logic programs, ...

We define the independence-reducibility based on a modification of key dependencies, which has better computational properties and is more practically useful than the original one based on key dependencies. Using this modification as a tool, we design ...

The weak instance model is a framework to consider the relations in a database as a whole, regardless of the way attributes are grouped in the individual relations. Queries and updates can be performed involving any set of attributes. The management of ...

External single-input single-output sorts can use multiple processors each with a large tournament replacement-selection in memory, and each with private disks to sort an input stream in linear elapsed time. Of course, increased numbers of processors, ...

Volcano is a new dataflow query processing system we have developed for database systems research and education. The uniform interface between operators makes Volcano extensible by new operators. All operators are designed and coded as if they were ...

Transactions have been rigorously defined and extensively studied in the database and transaction processing literature, but little has been said about the handling of the requests for transaction execution in commercial TP systems, especially ...

With recent declines in the cost of semiconductor memory and the increasing need for high performance I/O disk systems, it makes sense to consider the design of large caches. In this paper, we consider the effect of caching writes. We show that cache ...

This paper is concerned with the parallel evaluation of datalog rule programs, mainly by processors that are interconnected by a communication network. We introduce a paradigm, called data-reduction, for the parallel evaluation of a general datalog ...

This paper presents several complementary methods for the parallel, bottom-up evaluation of Datalog queries. We introduce the notion of a discriminating predicate, based on hash functions, that partitions the computation between the processors in order ...

In a multilevel secure database management system based on the replicated architecture, there is a separate database management system to manage data at or below each security level, and lower level data are replicated in all databases containing higher ...

For next generation information systems, concurrency control mechanisms are required to handle high level abstract operations and to meet high throughput demands. The currently available single level concurrency control mechanisms for reads and writes ...

The role of database knowledge is usually limited to the evaluation of data queries. In this paper we argue that when this knowledge is of substantial volume and complexity, there is genuine need to query this repository of information. Moreover, since ...

An extension of logic programming, called “ordered logic programming”, which includes some abstractions of the object-oriented paradigm, is presented. An ordered program consists of a number of modules (objects), where each module is composed by a ...

Recently, a number of extensions to the traditional transaction model have been proposed to support new information-intensive applications such as CAD/CAM and software development. However, these extended models capture only a subset of interactions ...

This paper addresses the problem of organising and controlling activities that involve multiple steps of processing and that typically are of long duration. We explore the use of triggers and transactions to specify and organize such long-running ...

A model of a multidatabase system is defined in which each local DBMS uses the two-phase locking protocol Locks are released by a global transaction only after the transaction commits or aborts at each local site. Failures may occur during the ...

LOGRES is a new project for the development of extended database systems which is based on the integration of the object-oriented data modelling paradigm and of the rule-based approach for the specification of queries and updates.

The data model supports ...

Deductive databases provide a formal framework to study rule-based query languages that are extensions of first-order logic. However, deductive database languages and their current implementations do not seem appropriate for improving the development of ...

We define the magic-sets transformation for traditional relational systems (with duplicates, aggregation and grouping), as well as for relational systems extended with recursion. We compare the magic-sets rewriting to traditional optimization techniques ...

We propose incorporating a production rules facility into a relational database system. Such a facility allows definition of database operations that are automatically executed whenever certain conditions are met. In keeping with the set-oriented ...

Forward-chaining rule systems must test each newly asserted fact against a collection of predicates to find those rules that match the fact. Expert system rule engines use a simple combination of hashing and sequential search for this matching. We ...

This paper demonstrates that a simple rule system can be constructed that supports a more powerful view system than available in current commercial systems. Not only can views be specified by using rules but also special semantics for resolving ...

We determine when a join/outerjoin query can be expressed unambiguously as a query graph, without an explicit specification of the order of evaluation. To do so, we first characterize the set of expression trees that implement a given join/outerjoin ...

In this paper we describe three pointer-based join algorithms that are simple variants of the nested-loops, sort-merge, and hybrid-hash join algorithms used in relational database systems. Each join algorithm is described and an analysis is carried out ...