A Review of integrity constraint maintenance and view updating techniques

Two interrelated problems may arise when updating a database. On one hand, when an update is applied to the database, integrity constraints may become violated. In such case, the integrity constraint maintenance approach tries to obtain additional updates to keep integrity constraints satisfied. On the other hand, when updates of derived or view facts are requested, a view updating mechanism must be applied to translate the update request into correct updates of the underlying base facts. This survey reviews the research performed on integrity constraint maintenance and view updating. It is proposed a general framework to classify and to compare methods that tackle integrity constraint maintenance and/or view updating. Then, we analyze some of these methods in more detail to identify their actual contribution and the main limitations they may present.Postprint (published version

Updates by Reasoning about States

It has been argued that some sort of control must be introduced in order to perform update operations in deductive databases. Indeed, many approaches rely on a procedural semantics of rule based languages and often perform updates as side-effects. Depending on the evaluation procedure, updates are generally performed in the body (top-down evaluation) or in the head of rules (bottom-up evaluation). We demonstrate that updates can be specified in a purely declarative manner using standard model based semantics without relying on procedural aspects of program evaluation. The key idea is to incorporate states as first-class objects into the language. This is the source of the additional expressiveness needed to define updates. We introduce the update language Statelog+-, discuss various domains of application and outline how to implement computation of the perfect model semantics for Statelog+- programs

A Logical Approach to Cooperative Information Systems

``Cooperative information system management'' refers to the capacity of several computing systems to communicate and cooperate in order to acquire, store, manage, query data and knowledge. Current solutions to the problem of cooperative information management are still far from being satisfactory. In particular, they lack the ability to fully model cooperation among heterogeneous systems according to a declarative style. The use of a logical approach to model all aspects of cooperation seems very promising. In this paper, we de®ne a logical language able to support cooperative queries, updates and update propagation. We model the sources of information as deductive databases, sharing the same logical language to ex- press queries and updates, but containing independent, even if possibly related, data. We use the Obj-U-Datalog (E. Bertino, G. Guerrini, D. Montesi, Toward deductive object data- bases, Theory and Practice of Object Systems 1 (1) (1995) 19±39) language to model queries and transactions in each source of data. Such language is then extended to deal with active rules in the style of Active-U-Datalog (E. Bertino, B. Catania, V. Gervasi, A. Ra aet a, Ac- tive-U-Datalog: Integrating active rules in a logical update language, in: B. Freitag, H. Decker, M. Kifer, A. Voronkov (Eds.), LBCS 1472: Transactions and Change in Login Databases, 1998, pp. 106±132), interpreted according to the PARK semantics proposed in G. Gottlob, G. Moerkotte, V.S. Subrahmanian (The PARK semantics for active rules, in: P.M.G. Apers, M. Bouzeghoub, G. Gardarin (Eds.), LNCS 1057: Proceedings of the Fifth International Con- ference on Extending Database Technology, 1996, pp. 35±55). By using active rules, a system can e ciently perform update propagation among di erent databases. The result is a logical environment, integrating active and deductive rules, to perform update propagation in a cooperative framework

On specifying database updates

AbstractWe address the problem of formalizing the evolution of a database under the effect of an arbitrary sequence of update transactions. We do so by appealing to a first-order representation language called the situation calculus, which is a standard approach in artificial intelligence to the formalization of planning problems. We formalize database transactions in exactly the same way as actions in the artificial intelligence planning domain. This leads to a database version of the frame problem in artificial intelligence. We provide a solution to the frame problem for a special, but substantial, class of update transactions. Using the axioms corresponding to this solution, we provide procedures for determining whether a given sequence of update transactions is legal, and for query evaluation in an updated database. These procedures have the desirable property that they appeal to theorem-proving only with respect to the initial database state.We next address the problem of proving properties true in all states of the database. It turns out that mathematical induction is required for this task, and we formulate a number of suitable induction principles. Among those properties of database states that we wish to prove are the standard database notions of static and dynamic integrity constraints. In our setting, these emerge as inductive entailments of the database.Finally, we discuss various possible extensions of the approach of this paper, including transaction logs and historical queries, the complexity of query evaluation, actualized transactions, logic programming approaches to updates, database views, and state constraints

A unifying approach for queries and updates in deductive databases

This dissertation presents a unifying approach to process (recursive) queries and updates in a deductive database. To improve query performance, a combined top-down and bottom-up evaluation method is used to compile rules into iterative programs that contain relational algebra operators. This method is based on the lemma resolution that retains previous results to guarantee termination.Due to locality in database processing, it is desirable to materialize frequently used queries against views of the database. Unfortunately, if updates are allowed, maintaining materialized view tables becomes a major problem. We propose to materialize views incrementally, as queries are being answered. Hence views in our approach are only partially materialized. For such views, we design algorithms to perform updates only when the underlying view tables are actually affected.We compare our approach to two conventional methods for dealing with views: total materialization and query-modification. The first method materializes the entire view when it is defined while the second recomputes the view on the fly without maintaining any physical view tables. We demonstrate that our approach is a compromise between these two methods and performs better than either one in many situations.It is also desirable to be able to update views just like updating base tables. However, view updates are inherently ambiguous and the semantics of update propagation on recursively defined views were not well understood in the past. Using dynamic logic programming and lemma resolution, we are able to define the semantics of recursive view updates. These are expressed in the form of update translators specified by the database administrator when the view is defined. To guarantee completeness, we identify a subset of safe update translators. We prove that this subset of translators always terminate and are complete

Disjunctively incomplete information in relational databases: modeling and related issues

In this dissertation, the issues related to the information incompleteness in relational databases are explored. In general, this dissertation can be divided into two parts. The first part extends the relational natural join operator and the update operations of insertion and deletion to I-tables, an extended relational model representing inclusively indefinite and maybe information, in a semantically correct manner. Rudimentary or naive algorithms for computing natural joins on I-tables require an exponential number of pair-up operations and block accesses proportional to the size of I-tables due to the combinatorial nature of natural joins on I-tables. Thus, the problem becomes intractable for large I-tables. An algorithm for computing natural joins under the extended model which reduces the number of pair-up operations to a linear order of complexity in general and in the worst case to a polynomial order of complexity with respect to the size of I-tables is proposed in this dissertation. In addition, this algorithm also reduces the number of block accesses to a linear order of complexity with respect to the size of I-tables;The second part is related to the modeling aspect of incomplete databases. An extended relational model, called E-table, is proposed. E-table is capable of representing exclusively disjunctive information. That is, disjunctions of the form P[subscript]1\mid P[subscript]2\mid·s\mid P[subscript]n, where ǁ denotes a generalized logical exclusive or indicating that exactly one of the P[subscript]i\u27s can be true. The information content of an E-table is precisely defined and relational operators of selection, projection, difference, union, intersection, and cartisian product are extended to E-tables in a semantically correct manner. Conditions under which redundancies could arise due to the presence of exclusively disjunctive information are characterized and the procedure for resolving redundancies is presented;Finally, this dissertation is concluded with discussions on the directions for further research in the area of incomplete information modeling. In particular, a sketch of a relational model, IE-table (Inclusive and Exclusive table), for representing both inclusively and exclusively disjunctive information is provided

El Mètode dels esdeveniments per a l'Actualització de vistes en bases de dades deductives

En esta tesis se presenta un nuevo método, llamado método de los eventos, para la actualización de vistas en bases de datos deductivas. Este método aumenta la base de datos con un conjunto de reglas, llamadas reglas de transición y de evento, que definen explícitamente las inserciones y las supresiones inducidas por una modificación de la base de datos. Mediante estas reglas, se utiliza la resolución SIDNF para obtener todas las traducciones mínimas que satisfacen una petición de actualización de vista.Una de las contribuciones principales de esta tesis es la demostración del hecho que el método de los eventos es completo en bases de datos estratificados. Es decir, en este tipo de bases de datos dicho método obtiene todas las traducciones validas. Otras ventajas importantes del método son la incorporación de la comprobación de integridad en el proceso de traducción, el tratamiento uniforme de inserciones y supresiones, la posibilidad de prevenir efectos laterales y la traducción de peticiones de modificación de vista.Por todas estas razones, se puede decir que el método de los eventos tiene todo el poder de los métodos propuestos hasta el momento actual para la utilización de vistas en bases de datos deductivas, pero sin presentar algunas de sus limitaciones

ULTRA - A Logic Transaction Programming Language

Rule-based language for the specification of complex database updates and transactions. Formal treatment of the syntax and the declarative semanticsRegelbasierte Sprache zur Spezifikation komplexer Datenbank-Operationen und Transaktionen. Formle Behandlung von Syntax und deklarativer Semantik

Inkrementelle Integritätsprüfung und Sichtenaktualisierung in SQL

Zentrales Problem der Implementierung von Integritätsbedingungen und materialisierten Sichten ist die effiziente Reaktion auf Basisfakten-änderungen. Ändert sich ein Basisfakt durch Einfügung, Löschung oder Modifikation, so müssen die Integritätsbedingungen geprüft und die abgeleiteten und gespeicherten Fakten materialisierter Sichten aktualisiert werden. Da die Dauer der Integritätsprüfung und Sichten-aktualisierung unmittelbar die Ausführungsdauer einer Transaktion beeinflußt, ist eine effiziente Durchführung von entscheidender Bedeutung. Effiziente Verfahren zur Integritätsprüfung und Aktualisierung materialisierter Sichten gehören seit mehr als 15 Jahren zu den wichtigsten Problemen der Forschungen zu deduktiven Datenbanken. Die im Kontext von Datalog und Relationaler Algebra entwickelten inkrementellen Verfahren haben jedoch bislang kaum Anwendung in SQL gefunden. Dies zeigt sich an den funktional sehr beschränkten Implementierungen beider Konzepte in SQL-basierten Datenbank-systemen kommerzieller Hersteller. Zentrale Idee inkrementeller Ansätze ist, dass Integritätsprüfung und Sichtenaktualisierung nur für die aktuell geänderten Fakten durchgeführt werden. Zu diesem Zweck werden im Rahmen eines Änderungspropagierungsprozesses die durch Basisfaktenänderungen induzierten Änderungen abgeleiteter Fakten ermittelt. Da bei den bisherigen inkrementellen Verfahren SQL-spezifische Konzepte wie das SQL-Transaktions- und Integritätskonzept nicht berücksichtigt wurden, ist eine Anwendung dieser Verfahren in SQL nicht direkt möglich. Aus diesem Grund werden im Rahmen der vorgelegten Dissertation inkrementelle Verfahren zur effizienten Integritätsprüfung und Sichtenaktualisierung im Kontext von SQL entwickelt. Bei den Verfahrensentwürfen werden SQL-spezifische Systemeigenschaften unverändert berücksichtigt. Die Implementierung dieser Verfahren in SQL-basierten, kommerziellen Datenbanksystemen würde diese Systeme funktional um leistungsfähige Komponenten zur Integritätsprüfung und zur Simulation und Aktualisierung materialisierter Sichten erweitern