MOD

The paper deals with the problem of evaluating how the originality of the attributes of a relation, i.e. the number of distinct values in each attribute, is affected by relational operations that reduce the cardinality of the relation. This is indeed an ...

Modern database systems use transactions to achieve a high degree of fault-tolerance. Many modern programming languages and systems provide garbage collected heap storage, which frees the programmer from the job of explicitly deallocating storage. In ...

We consider distributed or parallel processing of datalog queries. We address this issue by decomposing databases into a number of subdatabases such that the computation of a program on a database can be achieved by unioning its independent evaluations ...

ODE is a database system and environment based on the object paradigm. It offers one integrated data model for both database and general purpose manipulation. The database is defined, queried and manipulated in the database programming language O++ ...

Machiavelli is a polymorphically typed programming language in the spirit of ML, but supports an extended method of type inferencing that makes its polymorphism more general and appropriate for database applications. In particular, a function that ...

CLASSIC is a data model that encourages the description of objects not only in terms of their relations to other known objects, but in terms of a level of intensional structure as well. The CLASSIC language of structured descriptions permits i) partial ...

We consider those database environments in which queries have strict timing constraints, and develop a time-constrained query evaluation methodology. For aggregate relational algebra queries, we describe a time constrained query evaluation algorithm. ...

We extend the relational model of data to allow classes as attribute values, thereby permitting the representation of hierarchies of objects. Inheritance, including multiple inheritance with exceptions, is clearly supported. Facts regarding classes of ...

Interactive use of relational database management systems (DBMS) requires a user to be knowledgeable about the semantics of the application represented in the database. In many cases, however, users are not trained in the application field and are not ...

We compare two high-availability techniques for recovery from media failures in database systems. Both techniques achieve high availability by having two copies of all data and indexes, so that recovery is immediate. “Mirrored declustering” spreads two ...

In this paper we analyze and compare four parallel join algorithms. Grace and Hybrid hash represent the class of hash-based join methods, Simple hash represents a looping algorithm with hashing, and our last algorithm is the more traditional sort-merge. ...

While several distributed (or 'shared nothing') database machines exist in the form of prototypes or commercial products, and a number of distributed concurrency control algorithms are available, the effect of parallelism on concurrency control ...

We propose a database logic which accounts in a clean declarative fashion for most of the “object-oriented” features such as object identity, complex objects, inheritance, methods, etc. Furthermore, database schema is part of the object language, which ...

A formal framework for studying the expressive power and complexity of OODB queries is developed. Three approaches to modeling sets are articulated and compared. The class of regular OODB schemas supports the explicit representation of set-valued types. ...

We demonstrate the power of object identities (oid's) as a database query language primitive. We develop an object-based data model, whose structural part generalizes most of the known complex-object data models: cyclicity is allowed in both its schemas ...

We investigate here functional deductive databases: an extension of DATALOG capable of representing infinite phenomena. Rules in functional deductive databases are Horn and predicates can have arbitrary unary and limited k-ary function symbols in one ...

Computing queries from derived relations, optimizing queries from a group of queries, and updating materialized views are important database problems and have attracted much attention. One thing common to these problems is their demand to quickly solve ...

Database applications often require to evaluate queries containing quantifiers or disjunctions, e.g., for handling general integrity constraints. Existing efficient methods for processing quantifiers depart from the relational model as they rely on non-...

In the majority of research work done on logic programming and deductive databases, it is assumed that the set of rules defined by the user is consistent, i.e., that no contradictory facts can be inferred by the rules. In this paper, we address the ...

The HiPAC project is investigating active, time-constrained database management. An active DBMS is one which automatically executes specified actions when specified conditions arise. HiPAC has proposed Event-Condition-Action (ECA) rules as a formalism ...

This paper presents a language for specifying database updates, queries and rule triggers, and describes how triggers can be compiled into an efficient mechanism. The rule language allows specification of both state and transition constraints as special ...

We present an algorithm for the efficient evaluation of a useful subset of recursive queries. Like the magic sets transformation, the algorithm consists of a rewriting phase followed by semi-naive bottom-up evaluation of the resulting rules. We prove ...

Traversal recursion is a class of recursive queries where the evaluation of the query involves traversal of a graph or a tree. This limited type of recursion arises in many applications. In this report we investigate a simple file structure that ...

We argue that accessing the transitive closure of relationships is an important component of both databases and knowledge representation systems in Artificial Intelligence. The demands for efficient access and management of large relationships motivate ...

A simple model for representing the hierarchical structure of information is proposed. This model, called the grammatical model, is based on trees that are generated by grammars; the grammars describe the hierarchy of the information represented by the ...

The nested relational model provides a better way to represent complex objects than the (flat) relational model, by allowing relations to have relation-valued attributes. A recursive algebra for nested relations that allows tuples at all levels of ...

The paper extends nested relations for managing temporal variation of complex objects. It combines the research in temporal databases and nested relations for nontraditional database applications. The basic modelling construct is a temporal atom as an ...

Spatial objects other than points and boxes can be stored in spatial indexes, but the techniques usually require the use of approximations that can be arbitrarily bad. This leads to poor performance and highly inaccurate responses to spatial queries. ...

Steady progress in the development of optical disc technology over the past decade has brought it to the point where it is beginning to compete directly with magnetic disc technology. WORM optical discs in particular, which permanently register ...

We present an access method designed to provide a single integrated index structure for a versioned timestamped database with a non-deletion policy. Historical data (superceded versions) is stored separately from current data. Our access method is ...