Jaume Sistac

Database Architecture for Data Warehousing: An Evolutionary Approach

In recent years, data warehouses have reached a prominent position in the database field, especially in the database industry. There are many issues in common between data warehouses and other database fields such as federated databases; in our opinion this fact has not been explored in its entirety. In this paper, an integrated database architecture in which data warehouses are part of the database is put forward. Instead of having data warehouses built using a database, we propose to have data warehouses defined as part of the database architecture; this architecture is defined as an extension of a federated database architecture.

Applying Transition Rules to Bitemporal Deductive Databases for Integrity Constraint Checking

A bitemporal deductive database is a deductive database that supports valid and transaction time. A set of facts to be inserted and/or deleted in a bitemporal deductive database can be done in a past, present or future valid time. This circumstance causes that the maintenance of database consistency becomes more hard. In this paper, we present a new approach to reduce the difficulty of this problem, based on applying transition and event rules, which explicitly define the insertions and deletions given by a database update. Transition rules range over all the possible cases in which an update could violate some integrity contraint. Although, we have a large amount of transition rules, for each one we argue its utility or we eliminate it. We augment a database with this set of transition and event rules and then standard SLDNF resolution can be used to check satisfaction of integrity constraints.

An integrity constraint checking method for temporal deductive databases

The authors propose a method for integrity checking in the context of temporal deductive databases. A temporal deductive database is a deductive database that supports some aspect of time, in our case valid time, in which valid time is the time when the fact is true in the modelled reality. Their method augments a database with a set of transition and event rules, which explicitly define the insertions and deletions by database update. Standard SLDNF resolution can then be used to check satisfaction of integrity constraints. A temporal deductive database has to be consistent, that is, after performing an update the database must satisfy its set of integrity constraints. Using their method the temporal deductive database is always consistent because if a retroactive or proactive update violated some integrity constraint the update would be rejected.

The Dades/GP approach to automatic generation of information system prototypes from a deductive conceptual model

Abstract We describe the main issues we faced in the design and construction of the DADES/GP system. This system generates prototypes of Information Systems (IS). The input to the system is a deductive conceptual model of the IS written in the DADES language, which is also described in this paper. Several alternatives exist in the architecture of the prototype. Our system uses forward inference architecture, which allows an efficient production of outputs and is able to incorporate a number of optimization procedures.

Definition of deductive conceptual models of OODBs

The definition of deductive conceptual models (DCMs) using Prolog in order to specify different aspects of OODBs is proposed. The result of the specification process using this technique is an executable prototype of the system. Having a prototype directly available, along with the system specifications, is particularly useful in order to define additional elements in the context of OODBs (e.g. schema evolution, definition of derived classes definition of external schemas). The use of this technique is proposed mainly due to the difficulty of building prototypes of the mentioned elements over commercial OODBs. A brief example of a practical application of this technique-the specification of a conceptual schema definition system and its associated data model-is presented.

Definition of derived classes in OODBs

According to the ANSI/SPARC architecture, external schemas are derived from the database conceptual schema. In object-oriented databases (OODBs), an external schema map include classes defined in the conceptual schema just as it may also contain derived classes which are directly or indirectly defined on the basis of conceptual schema classes. In the definition of derived classes in OODBs three main issues have to be resolved, namely: the integration of derived classes with other classes in an object schema; the definition of classes with new objects; and the transmission of modifications between the objects in derived classes and those of the classes from which they are defined. A solution to the first issue was proposed by Samos (1998). In this paper, the two remaining issues are further studied and new conceptual level solutions are put forward. Our proposals are informally illustrated through some examples.