Database Systems

Silberschatz, Abraham; Korth, Henry F.; Sudarshan, S.

doi:10.1016/b0-12-227240-4/00028-9

Cited by 185 publications

(280 citation statements)

References 2 publications

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“…We will only sketch the basic concept for using this structure here. Instead of a space-consuming materialization of the Cartesian Product R × S, we materialize the Full Outer Join R 1 S which pads tuples for which no matching tuples in the other relation exist with null values (see, e.g., [5,17]). The result tuples obtained by the full outer-join operator again can be grouped into three classes: (1) those tuples ts, t ∈ R, s ∈ S, for which the join condition holds, (2) tuples from r for which no matching tuples in s exist, and (3) tuples from s for which no matching tuples in r exist.…”

Section: Joinsmentioning

confidence: 99%

“…Indeed, via mechanisms such as embedded SQL (see, e.g., [17]) database queries are compiled into applications. These queries can still make use of parameters entered by a user and which are typically used in selection conditions.…”

Section: Query Flexibilitymentioning

confidence: 99%

“…The data model underlying our approach is the relational data model (see, e.g., [5,17]). That is, we assume that the data owner and the publisher manage the data using a relational database management system (DBMS).…”

Section: Relational Databasesmentioning

confidence: 99%

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Authentic Third-Party Data Publication

Dévanbu

Gertz

Martel

et al. 2002

Data and Application Security

125

129

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Integrity critical databases, such as financial information, which are used in high-value decisions, are frequently published over the internet. Publishers of such data must satisfy the integrity, authenticity, and non-repudiation requirements of end clients. Providing this protection over public data networks is an expensive proposition. This is, in part, due to the difficulty of building and running secure systems. In practice, large systems can not be verified to be secure and are frequently penetrated. The negative consequences of a system intrusion at the publisher can be severe. The problem is further complicated by data and server replication to satisfy availability and scalability requirements.To our knowledge this work is the first of its kind to give general approaches for reduce the trust required of the publisher of large, infrequently updated databases. To do this, we separate the roles of owner and publisher. With a few digital signatures on the part of the owner and no trust required of the publisher, we give techniques based on Merkle hash trees, that publishers can use to provide authenticity and non-repudiation of the answer to a database query. This is done without requiring a key to be held in an on-line system, thereby reducing the impact due to the likely system penetration. By reducing the trust required of the publisher, our solution is a step towards the publication of large databases in a scalable manner.

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Section: Joinsmentioning

confidence: 99%

Section: Query Flexibilitymentioning

confidence: 99%

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Authentic Third-Party Data Publication

Dévanbu

Gertz

Martel

et al. 2002

Data and Application Security

125

129

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“…A distributed transaction may span several sites reading or updating data objects. A typical distributed transaction contains a sequence of database operations which must be processed at all of the participating sites or none of the sites to maintain the integrity of the database [29]. Assuming that each site maintains a log and a recovery procedure, commit protocols [17,29] ensure that all sites abort or commit a transaction unanimously despite multiple failures.…”

Section: Introductionmentioning

confidence: 99%

“…A typical distributed transaction contains a sequence of database operations which must be processed at all of the participating sites or none of the sites to maintain the integrity of the database [29]. Assuming that each site maintains a log and a recovery procedure, commit protocols [17,29] ensure that all sites abort or commit a transaction unanimously despite multiple failures. Several versions of commit protocols were proposed to improve performance dealing with various aspects such as site failures, blocking and even compensation.…”

Section: Introductionmentioning

confidence: 99%

Rigorous Design of Fault-Tolerant Transactions for Replicated Database Systems Using Event B

Yadav

Butler

2006

Rigorous Development of Complex Fault-Tolerant Systems

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Abstract. System availability is improved by the replication of data objects in a distributed database system. However, during updates, the complexity of keeping replicas identical arises due to failures of sites and race conditions among conflicting transactions. Fault tolerance and reliability are key issues to be addressed in the design and architecture of these systems. Event B is a formal technique which provides a framework for developing mathematical models of distributed systems by rigorous description of the problem, gradually introducing solutions in refinement steps, and verification of solutions by discharge of proof obligations. In this paper, we present a formal development of a distributed system using Event B that ensures atomic commitment of distributed transactions consisting of communicating transaction components at participating sites. This formal approach carries the development of the system from an initial abstract specification of transactional updates on a one copy database to a detailed design containing replicated databases in refinement. Through refinement we verify that the design of the replicated database confirms to the one copy database abstraction.

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Mining Web functional dependencies for flexible information access

Perugini

Ramakrishnan

2007

J. Am. Soc. Inf. Sci.

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We present an approach to enhancing information access through web structure mining in contrast to traditional approaches involving usage mining. Specifically, we mine the hardwired hierarchical hyperlink structure of websites to identify patterns of term-term cooccurrences we call web FDs (functional dependencies). Intuitively, a web FD 'x → y' declares that all paths through a site involving a hyperlink labeled x also contain a hyperlink labeled y. The complete set of FDs satisfied by a site help characterize (flexible and expressive) interaction paradigms supported by a site, where a paradigm is the set of explorable sequences therein. We describe algorithms for mining FDs, results from mining several hierarchical websites, and present several interface designs that can exploit such FDs to provide compelling user experiences.

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Database Systems

Cited by 185 publications

References 2 publications

Authentic Third-Party Data Publication

Authentic Third-Party Data Publication

Rigorous Design of Fault-Tolerant Transactions for Replicated Database Systems Using Event B

Mining Web functional dependencies for flexible information access

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