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In temporal XML databases, a retroactive update (i.e., modifying or deleting a past element) due to a detected error means that the database has included erroneous information during some period and, therefore, its consistency should be restored by correcting all errors and inconsistencies that have occurred in the past. Indeed, all processing that have been carried out during the inconsistency period and have used erroneous information have normally produced erroneous information. In this paper, we propose an approach which preserves data consistency in temporal XML databases. More precisely, after any retroactive update, the proposed approach allows (i) detecting and analyzing periods of database inconsistency, which result from that update, and (ii) repairing of all inconsistencies and recovery of all side effects.

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A retroactive update is an update that changes a past data. It is a common operation in both conventional and temporal databases. However, in temporal databases, a retroactive update is challenging since it could lead to data inconsistencies if the retroactively updated data were used for creating other data (like social contributions and taxes which are calculated based on the salaries of the employees). Such data inconsistencies must be repaired in order to preserve the database consistency. In this paper, we extend our previous approach on detecting and repairing automatically data inconsistencies that result from retroactive updates of multiversion temporal XML databases. The extension consists in: 1) providing an enhanced version of the architecture of our approach and explaining the process of handling a retroactive update; 2) showing how to extract data dependencies and how to use them in order to repair detected inconsistencies; 3) proposing a new log structure ensuring a complete and useful history of the executed transactions; 4) presenting a tool, named Retro-Update-Manager, that we have developed to prove technically our approach.Reference to this paper should be made as follows: Hamrouni, H., Brahmia, Z. and Bouaziz, R. (2018) 'A systematic approach to efficiently managing the effects of retroactive updates of time-varying data in multiversion XML databases', Int.

Purpose A temporal XML database could become an inconsistent model of the represented reality after a retroactive update. Such an inconsistency state must be repaired by performing corrective actions (e.g. payment of arrears after a retroactive salary increase) either immediately (i.e. at inconsistency detection time) or in a deferred manner, at one or several chosen repair times according to application requirements. The purpose of this work is to deal with deferred and multi-step repair of detected data inconsistencies. Design/methodology/approach A general approach for deferred and stepwise repair of inconsistencies that result from retroactive updates of currency data (e.g. the salary of an employee) in a valid-time or bitemporal XML database is proposed. The approach separates the inconsistency repairs from the inconsistency detection phase and deals with the execution of corrective actions, which also take into account enterprise’s business rules that define some relationships between data. Findings Algorithms, methods and support data structures for deferred and multi-step inconsistency repair of currency data are presented. The feasibility of the approach has been shown through the development and testing of a system prototype, named Deferred-Repair Manager. Originality/value The proposed approach implements a new general and flexible strategy for repairing detected inconsistencies in a deferred manner and possibly in multiple steps, according to varying user’s requirements and to specifications which are customary in the real world.

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