We define formal notions of temporal domain and temporal database, and use them to survey a wide spectrum of temporal query languages. We distinguish between an abstract temporal database and its concrete representations, and accordingly between abstract and concrete temporal query languages. We also address the issue of incomplete temporal information. 1 Introduction A temporal database is a repository of temporal information. A temporal query language is any query language for temporal databases. In this paper we propose a formal notion of temporal database and use this notion in surveying a wide spectrum of temporal query languages. The need to store temporal information arises in many computer applications. Consider, for example, records of various kinds: financial [37], personnel, medical [98], or judicial. Also, monitoring data, e.g., in telecommunications network management [4] or process control, has often a temporal dimension. There has been a lot of research in temporal dat...

: We present an efficient implementation method for temporal integrity constraints formulated in Past Temporal Logic. Although the constraints can refer to past states of the database, their checking does not require that the entire database history be stored. Instead, every database state is extended with auxiliary relations that contain the historical information necessary for checking constraints. Auxiliary relations can be implemented as materialized relational views. 1 Introduction Integrity constraints form an essential part of every database application. It is customary to distinguish between two kinds of constraints: static and temporal (or dynamic). Static constraints refer to the current state of the database, e.g.,"every manager is also an employee ", while temporal constraints may refer to past and future states in addition to the current state, e.g., "salaries of employees should never decrease" or "once a student drops out of the Ph.D. program, she should not be readmit...

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In this paper we propose two languages, called Future Temporal Logic (FTL) and Past Temporal Logic (PTL), for specifying temporal triggers. Some examples of trigger conditions that can be specified in our language are the following: "The value of a certain attribute increases by more than 10% in ten minutes", "A tuple that satisfies a certain predicate is added to the database at least 10 minutes before another tuple, satisfying a different condition, is added to the database". Such triggers are important for monitor and control applications. In addition to the languages, we present algorithms for processing the trigger conditions specified in these languages, namely, procedures for determining when the trigger conditions are satisfied. These methods can be added as a "temporal" component to an existing database management systems. A preliminary prototype of the temporal component that uses the FTL language has been built on top of Sybase running on SUN workstations. Index Terms: Acti...

In this paper, we present a unified formalism, based on Past Temporal Logic, for specifying conditions and events in the rules for active database system. This language permits specification of many time varying properties of database systems. It also permits specification of temporal aggregates. We present an efficient incremental algorithm for detecting conditions specified in this language. The given algorithm, for a subclass of the logic, was implemented on top of Sybase. 0 1 Introduction The most popular model of rules in active database systems is the ECA model [41, 6, 28, 5, 14, 18]. It defines a rule to consist of three parts, event, condition, and action. The semantics is that whenever the event happens, the condition (which is usually a database query) is evaluated, and if satisfied then the action is taken. The event may be composite and temporal, such as, transaction A starts after transaction B ended. However, the condition is static in the sense that it refers to the cu...

The system presented in this paper allows automatic and efficient translation of integrity constraints formulated in past temporal logic into rules of the Starburst DBMS. During the compilation the set of constraints is checked for the safe evaluation property. The result of the compilation is a set of Starburst SQL statements that define all the necessary rules needed for enforcing the given constraints. There is no need for an additional runtime constraint monitor. When the rules are activated, all updates to the database that violate any of the constraints are automatically rejected (i.e., the corresponding transaction is aborted). In addition to efficient implementation, this approach offers a clean separation of application programs and the integrity checking code. 1 Introduction Since the introduction of databases, the notions of data consistency and integrity constraints have been an playing important role in the database application design process. The constraints can usuall...

We analyze the computational feasibility of checking temporal integrity constraints formulated in some sublanguages of first-order temporal logic. Our results illustrate the impact of the quantifier pattern on the complexity of this problem. The presence of a single quantifier in the scope of a temporal operator makes the problem undecidable. On the other hand, if no quantifiers are in the scope of a temporal operator and all the quantifiers are universal, temporal integrity checking can be done in exponential time. 1 Introduction As temporal databases become more widely used in practice [27, 28], the need arises to address database integrity issues that are specific to such databases. In particular, it is necessary to generalize the standard notion of static integrity (involving single database states) to temporal integrity (involving sequences of database states). This work is the first attempt to date to analyze the computational feasibility of checking temporal integrity constrain...

An important feature of many advanced active database prototypes is support for rules triggered by complex patterns of events. Their composite event languages provide powerful primitives for event-based temporal reasoning. In fact, with one important exception, their expressive power matches and surpasses that of sophisticated languages offered by Time Series Management Systems (TSMS), which have been extensively used for temporal data analysis and knowledge discovery. This exception pertains to temporal aggregation, for which, current active database systems offer only minimal support, if any. In this paper, we introduce the language TREPL, which addresses this problem. The TREPL prototype, under development at UCLA, offers primitives for temporal aggregation that exceed the capabilities of state-of-the-art composite event languages, and are comparable to those of TSMS languages. TREPL also demonstrates a rigorous and general approach to the definition of composite event language sema...

Modern approaches to integrity monitoring suggest to generate triggers from constraints as part of database design and to utilize constraint simplification techniques for trigger optimization. Such proposals, however, have been restricted to static conditions which constrain single states only. In this paper, we show how to derive triggers from dynamic integrity constraints which describe properties of state transitions or state sequences and which can be specified by formulae in temporal logic. Such constraints can equivalently be transformed into transition graphs which describe such life cycles of database objects that are admissible with respect to the constraints: Nodes correspond to situations in life cycles, and edges give the (changing) conditions under which a change into another situation is allowed. If object situations are stored, integrity maintaining triggers can be generated from transition graphs for all situations and all critical database operations. Additionally, new...

The enforcement of semantic integrity constraints in data and knowledge bases constitutea a major performance bottleneck. Integrity constraint simplification methods aim at reducing the complexity of formula evaluation at run-time. This paper proposes such a simplification method for large and semanti-cally rich knowledge bases. Structural, temporal and asser-tional knowledge in the form of deductive rules and integrity constraints, is represented in Telos, a hybrid language for knowledge representation. A compilation method performs a number of syntactic, semantic and temporal transforma-tions to integrity constraints and deductive rules, and orga-nizes simplified forms in a dependence graph that allows for efficient computati.on of implicit updates. Precomputation of potential implicit updates at compile time is possible by com-puting the dependence graph transitive closure. To account for dynamic changes to the dependence graph by updates of constraints and rules, we propose efficient algorithms for the incremental maintenance of the computed transitive closure.