: 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...

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...

In a class hierarchy, a “role set ” is t,he set of classes where an object may reside simultaneously. A “migration pattern ” is a sequence of role sets. A “migration inventory, ” which is a set, of migrat,ion patterns, is viewed as a dynamic const,raintm on ohjrct migration. A set of transact ious is “sound ” wrt a11 inventory if it. generates only pat.t.t~rns in the invrntory; “complete ” if all pat,terns in the invent,ory can be generated. An initial stucly on characterizing migration inventories of transact,ions is presented. Three update languages are considered: SL which contains five operat,ors, CSL+ which ext rn(ls SL wit.h posit.ivc conditionals, and CSL which allows hot,h positive and negative condit.ionals. Four kinds of invent.orics are studied based on ln~znrss and znj~~,rtl~ntr s/art. It is shown that inventories produced by SL t,ransactions are regular and every regular inventory can be generated by SL transactions. Soundness and complet,eness for SL t,ransactions are decidahlt3. lnvc\llt,orics gpnrrated by CSL (CSL+) t,ra.nsactions arc r.e‘. and every r.e. inventory can be generat,rd by (:SL+ (CSL) transa.ctions under nonimmediate st,art,. It is also show t,hat, every r.e. immediate-start invent,ory can be obtained by a left quotient, of t,he invent,ory of CSL+ (CSL) transactions hy a regular seb. The exact, charact#erizat.ions are open. However, cvrry contrxl-frcr srt can be generat,ed. Soundness and rmllplPt~enms for ($1, (CSL+) t,ransa.ctions are undecidahlr. 1

In active database systems, events are used in ECA rules to specify the time to check the conditions of the rules. Composite events can be constructed in an intuitive way by applying event operators, such as and, or, sequence, etc., to primitive events. Where timing is important, these event operators may introduce ambiguity if there is no formal semantics defining the occurrence of the composite events. In this paper, we propose a formalism to specify a wider range of composite events with formal semantics in the logic RTL which is especially amenable for specifying timing constraints in real-time systems. The use of RTL to define the formal semantics also allows us to exploit compilation methods which can be used to translate the enabling conditions of ECA rules into timing constraints. Thus the detection of composite events can be handled by monitoring the corresponding timing constraints, a subject which has been explored in our previous work [18, 19]. A prototype implementation of...

: In this paper, we propose an event specification language, which incorporates a calendar algebra to conveniently allow complex temporal event descriptions. Other features of this language include allowing multiple events to occur at the same time as well as window and event counter constructs. The semantics of the language is also studied. We argue that semantics from intuition for event specification language is not sufficient due to its ambiguity in tracing reasons for event occurrence and over-triggering in some application circumstances. Based on this observation, we put forward a semantic decoration system to provide a modification for general semantics. A decoration system is a system of notations, called decorators, on the general semantics that impose additional constraints on when an event is viewed as triggered. The decoration system implicitly sets up relationship among occurrences of different events. This kind of relationship can not be expressed by most event specificat...

this paper, we survey our work on temporal integrity constraints in relational databases, done in the context of FirstOrder Temporal Logic (called FOTL hereafter). We have addressed both foundational and practical issues. 2 First-order temporal logic

. The paper presents a novel compilation scheme for temporal integrity constraints and deductive rules expressed in an interval-based first-order temporal logic. Compilation builds a dependence graph with simplified forms of the constraints and rules. This permits the compiletime simplification of the formulae that have to be verified at run-time, as well as the precomputation of potential implicit updates. We show how simplified forms can be obtained with respect to transactions made up of arbitrary sequences of basic updates. Additional optimization steps exploit the organization of simplified forms in dependence graphs. 1 Introduction The maintenance of semantic integrity is recognized as a cornerstone issue for the development of data bases and knowledge bases alike [11], [27], [18]. Integrity constraints express application dependent semantics that are not built into the data structures used to represent knowledge. Additionally, they constitute a means for controlling the quality...