Violations Of Integrity Constraints Research Articles

Detecting data errors

Data cleaning has played a critical role in ensuring data quality for enterprise applications. Naturally, there has been extensive research in this area, and many data cleaning algorithms have been translated into tools to detect and to possibly repair certain classes of errors such as outliers, duplicates, missing values, and violations of integrity constraints. Since different types of errors may coexist in the same data set, we often need to run more than one kind of tool. In this paper, we investigate two pragmatic questions: (1) are these tools robust enough to capture most errors in real-world data sets ? and (2) what is the best strategy to holistically run multiple tools to optimize the detection effort? To answer these two questions, we obtained multiple data cleaning tools that utilize a variety of error detection techniques. We also collected five real-world data sets, for which we could obtain both the raw data and the ground truth on existing errors. In this paper, we report our experimental findings on the errors detected by the tools we tested. First, we show that the coverage of each tool is well below 100%. Second, we show that the order in which multiple tools are run makes a big difference. Hence, we propose a holistic multi-tool strategy that orders the invocations of the available tools to maximize their benefit, while minimizing human effort in verifying results. Third, since this holistic approach still does not lead to acceptable error coverage, we discuss two simple strategies that have the potential to improve the situation, namely domain specific tools and data enrichment. We close this paper by reasoning about the errors that are not detectable by any of the tools we tested.

Analysing inconsistent information using distance-based measures

There have been a number of proposals for measuring inconsistency in a knowledgebase (i.e. a set of logical formulae). These include measures that consider the minimally inconsistent subsets of the knowledgebase, and measures that consider the paraconsistent models (3 or 4 valued models) of the knowledgebase. In this paper, we present a new approach that considers the amount by which each formula has to be weakened in order for the knowledgebase to be consistent. This approach is based on ideas of knowledge merging by Konienczny and Pino-Perez. We show that this approach gives us measures that are different from existing measures, that have desirable properties, and that can take the significance of inconsistencies into account. The latter is useful when we want to differentiate between inconsistencies that have minor significance from inconsistencies that have major significance. We also show how our measures are potentially useful in applications such as evaluating violations of integrity constraints in databases and for deciding how to act on inconsistency.

Constraint-preserving snapshot isolation

A method for detecting potential violations of integrity constraints of concurrent transactions running under snapshot isolation (SI) is presented. Although SI provides a high level of isolation, i...

English

4 ABSTRACT: This paper details about various methods prevailing in literature for efficient discovery of matching dependencies. The concept of matching dependencies (MDs) has recently been proposed for specifying matching rules for object identification. Similar to the functional dependencies with conditions, MDs can also be applied to various data quality applications such as detecting the violations of integrity constraints. The problem of discovering similarity constraints for matching dependencies from a given database instance is taken into consideration. This survey would promote a lot of research in the area of information mining.

English

This paper details about various methods prevailing in literature for efficient discovery of matching dependencies. The concept of matching dependencies (MDs) has recently been proposed for specifying matching rules for object identification. Similar to the functional dependencies with conditions, MDs can also be applied to various data quality applications such as detecting the violations of integrity constraints. The problem of discovering similarity constraints for matching dependencies from a given database instance is taken into consideration. This survey would promote a lot of research in the area of information mining

English

4 ABSTRACT: This paper details about various methods prevailing in literature for efficient discovery of matching dependencies. The concept of matching dependencies (MDs) has recently been proposed for specifying matching rules for object identification. Similar to the functional dependencies with conditions, MDs can also be applied to various data quality applications such as detecting the violations of integrity constraints. The problem of discovering similarity constraints for matching dependencies from a given database instance is taken into consideration. This survey would promote a lot of research in the area of information mining.

Efficient discovery of similarity constraints for matching dependencies

The concept of matching dependencies (mds) has recently been proposed for specifying matching rules for object identification. Similar to the functional dependencies (with conditions), mds can also be applied to various data quality applications such as detecting the violations of integrity constraints. In this paper, we study the problem of discovering similarity constraints for matching dependencies from a given database instance. First, we introduce the measures, support and confidence, for evaluating the utility of mds in the given data. Then, we study the discovery of mds with certain utility requirements of support and confidence. Exact algorithms are developed, together with pruning strategies to improve the time performance. Since the exact algorithm has to traverse all the data during the computation, we propose an approximate solution which only uses part of the data. A bound of relative errors introduced by the approximation is also developed. Finally, our experimental evaluation demonstrates the efficiency of the proposed methods.

View updates and constraint validations in collaborative design environments

In collaborative designs that are either intracompany or intercompany, data security and integrity validation are two major concerns. Even though design views can be used effectively for access controls, view updates may cause violation of integrity constraints defined for the base designs. This article focuses on the validation of integrity constraints after view updates. Following standard for the exchange of product model data methodologies, information model is defined by EXPRESS and views are defined by EXPRESS-X. Shared design data are stored in a relational database system (e.g. Oracle 11g XE). The integrity constraints defined in EXPRESS schema are translated into UNIQUE and CHECK and triggers in SQL. Then, they are automatically validated after view updates. Because the paradigm presented in this article is based on open standards such as EXPRESS, EXPRESS-X, and SQL, it is independent from any proprietary system and suitable for collaborative design environments that consist of heterogeneous systems.

Serializable snapshot isolation for replicated databases in high-update scenarios

Many proposals for managing replicated data use sites running the Snapshot Isolation (SI) concurrency control mechanism, and provide 1-copy SI or something similar, as the global isolation level. This allows good scalability, since only ww -conflicts need to be managed globally. However, 1-copy SI can lead to data corruption and violation of integrity constraints [5]. 1-copy serializability is the global correctness condition that prevents data corruption. We propose a new algorithm Replicated Serializable Snapshot Isolation (RSSI) that uses SI at each site, and combines this with a certification algorithm to guarantee 1-copy serializable global execution. Management of ww -conflicts is similar to what is done in 1-copy SI. But unlike previous designs for 1-copy serializable systems, we do not need to prevent all rw -conflicts among concurrent transactions. We formalize this in a theorem that shows that many rw -conflicts are indeed false positives that do not risk non-serializable behavior. Our proposed RSSI algorithm will only abort a transaction when it detects a well-defined pattern of two consecutive rw -edges in the serialization graph. We have built a prototype that integrates our RSSI with the existing open-source Postgres-R(SI) system. Our performance evaluation shows that there is a worst-case overhead of about 15% for getting full 1-copy serializability as compared to 1-copy SI in a cluster of 8 nodes, with our proposed RSSI clearly outperforming the previous work [6] for update-intensive workloads.

Maintaining control while delegating trust

We introduce the use, monitoring, and enforcement of integrity constraints in trust management-style authorization systems. We consider what portions of the policy state must be monitored to detect violations of integrity constraints. Then, we address the fact that not all participants in a trust-management system can be trusted to assist in such monitoring, and show how many integrity constraints can be monitored in a conservative manner so that trusted participants detect and report if the system enters a policy state from which evolution in unmonitored portions of the policy could lead to a constraint violation.

Efficient Integrity Checking for Essential MOF + OCL in Software Repositories.

The efficient detection of run-time violations of integrity constraints (or their avoidance in the first place) has not been satisfactorily addressed for the combination of object model and constraint definition language most widely accepted in industry, namely OMG’s Essential MOF and Object Constraint Language (OCL). We identify the dimensions relevant to this problem, and classify existing proposals by their position in the solution space. After this comparative survey, we propose a solution for the efficient integrity checking of invariants expressed in OCL over the Essential MOF data model, and describe the software architecture of its implementation using object-relational mapping technology.