We present a simple algorithm for maintaining a replicated distributed dictionary which achieves high availability of data, rapid processing of atomic actions, efficient utilization of storage, and tolerance to node or network failures including lost or duplicated messages. It does not require transaction logs, synchronized clocks, or other complicated mechanisms for its operation. It achieves consistency contraints which are considerably weaker than serial consistency but nonetheless are adequate for many dictionary applications such as electronic appointment calendars and mail systems. The degree of consistency achieved depends on the particular history of operation of the system in a way that is intuitive and easily understood. The algorithm implements a "best effort" approximation to full serial consistency, relative to whatever internode communication has successfully taken place, so the semantics are fully specified even under partial failure of the system. Both the correctness of the algorithm and the utility of such weak semantics depend heavily on special properties of the dictionary operations.
{"title":"Sacrificing serializability to attain high availability of data in an unreliable network","authors":"M. Fischer, Alan Michael","doi":"10.1145/588111.588124","DOIUrl":"https://doi.org/10.1145/588111.588124","url":null,"abstract":"We present a simple algorithm for maintaining a replicated distributed dictionary which achieves high availability of data, rapid processing of atomic actions, efficient utilization of storage, and tolerance to node or network failures including lost or duplicated messages. It does not require transaction logs, synchronized clocks, or other complicated mechanisms for its operation. It achieves consistency contraints which are considerably weaker than serial consistency but nonetheless are adequate for many dictionary applications such as electronic appointment calendars and mail systems. The degree of consistency achieved depends on the particular history of operation of the system in a way that is intuitive and easily understood. The algorithm implements a \"best effort\" approximation to full serial consistency, relative to whatever internode communication has successfully taken place, so the semantics are fully specified even under partial failure of the system. Both the correctness of the algorithm and the utility of such weak semantics depend heavily on special properties of the dictionary operations.","PeriodicalId":126896,"journal":{"name":"Proceedings of the 1st ACM SIGACT-SIGMOD symposium on Principles of database systems","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126223536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
‘l’hc IISMI IllOddS for distributed dak?basc~ [RSIJG] arc ba>ed on a set of “entities” distributed amuunL the nodes of a network. ‘l‘hcse entities arc xcwcd by USCI’S OF the database through “trcuxactions”, which are ccr& SCquCnccS of steps (“actions”) involviiig the jndiidllal entities. ‘L‘hC Steps arc grouped into trxwctions for twu disdnct purpuscs. i.jr,q a tramaction is t6cd as a unit of rccovcry: tither all of the steps of a transaction should bc carricci out, or none of them should; tl1llS, jf a transaction cannot bc complctcd. its initial steps must bc “undone” in some way. Second, a transaction is used to define atomicity: all of the !Xci)s of a transaction furm a logical atomic unit in the sense that it should appear to users of the database that all of thcsc steps are carried 014 consccutivcly, without any intcrvcning steps of other lransactions. This rcquircmcnt that transactions appear to be atomic is called “scriali/nbility” in the hlcralure [IGLT. RSI., IIG], and has been widely acccptcd as an important correctness criterion for distributed
{"title":"Multilevel atomicity","authors":"N. Lynch","doi":"10.1145/588111.588123","DOIUrl":"https://doi.org/10.1145/588111.588123","url":null,"abstract":"‘l’hc IISMI IllOddS for distributed dak?basc~ [RSIJG] arc ba>ed on a set of “entities” distributed amuunL the nodes of a network. ‘l‘hcse entities arc xcwcd by USCI’S OF the database through “trcuxactions”, which are ccr& SCquCnccS of steps (“actions”) involviiig the jndiidllal entities. ‘L‘hC Steps arc grouped into trxwctions for twu disdnct purpuscs. i.jr,q a tramaction is t6cd as a unit of rccovcry: tither all of the steps of a transaction should bc carricci out, or none of them should; tl1llS, jf a transaction cannot bc complctcd. its initial steps must bc “undone” in some way. Second, a transaction is used to define atomicity: all of the !Xci)s of a transaction furm a logical atomic unit in the sense that it should appear to users of the database that all of thcsc steps are carried 014 consccutivcly, without any intcrvcning steps of other lransactions. This rcquircmcnt that transactions appear to be atomic is called “scriali/nbility” in the hlcralure [IGLT. RSI., IIG], and has been widely acccptcd as an important correctness criterion for distributed","PeriodicalId":126896,"journal":{"name":"Proceedings of the 1st ACM SIGACT-SIGMOD symposium on Principles of database systems","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128890053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many results in relational database theory on the structure of dependencies, query languages, and databases in general have now been established. However, neither (a) the reliance of these results on various assumptions, nor (b) the desirability or reasonableness of these assumptions themselves have been closely examined. These assumptions are nontrivial: examples include the universal relation assumption and the lossless join assumption.The purpose of the present paper is to clarify many of the existing assumptions, and point out weaknesses. This is desirable both to harden the statements of previous results, and to evaluate recent suggestions that certain assumptions (such as the acyclic JD assumption) may be useful for modeling "real world" databases. Specifically, studies are made of assumptions made for (1) universal relations, (2) functional dependency inference, and (3) decomposition theory. We show that:• Some assumptions (such as uniqueness of relationships among attributes) can be more powerful than they appear;• common treatment of FDs is sometimes inappropriate, and for example FD inferences such as {A → B, B → C} |= A → C can be incorrect;• the 'decomposition' approach to design may be hard to justify in real terms; and• Acyclic JDs may have drawbacks in eliminating ambiguity in queries and in modeling real enterprises.It is hoped that this exposition will help clarify some confusing issues in this field, and will lead to a better understanding of which assumptions are reasonable and useful in modeling the "real world".
{"title":"Assumptions in relational database theory","authors":"P. Atzeni, D. S. Parker","doi":"10.1145/588111.588113","DOIUrl":"https://doi.org/10.1145/588111.588113","url":null,"abstract":"Many results in relational database theory on the structure of dependencies, query languages, and databases in general have now been established. However, neither (a) the reliance of these results on various assumptions, nor (b) the desirability or reasonableness of these assumptions themselves have been closely examined. These assumptions are nontrivial: examples include the universal relation assumption and the lossless join assumption.The purpose of the present paper is to clarify many of the existing assumptions, and point out weaknesses. This is desirable both to harden the statements of previous results, and to evaluate recent suggestions that certain assumptions (such as the acyclic JD assumption) may be useful for modeling \"real world\" databases. Specifically, studies are made of assumptions made for (1) universal relations, (2) functional dependency inference, and (3) decomposition theory. We show that:• Some assumptions (such as uniqueness of relationships among attributes) can be more powerful than they appear;• common treatment of FDs is sometimes inappropriate, and for example FD inferences such as {A → B, B → C} |= A → C can be incorrect;• the 'decomposition' approach to design may be hard to justify in real terms; and• Acyclic JDs may have drawbacks in eliminating ambiguity in queries and in modeling real enterprises.It is hoped that this exposition will help clarify some confusing issues in this field, and will lead to a better understanding of which assumptions are reasonable and useful in modeling the \"real world\".","PeriodicalId":126896,"journal":{"name":"Proceedings of the 1st ACM SIGACT-SIGMOD symposium on Principles of database systems","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132846200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Session details: Session 1","authors":"Shin-Cheng Mu","doi":"10.1145/3248282","DOIUrl":"https://doi.org/10.1145/3248282","url":null,"abstract":"","PeriodicalId":126896,"journal":{"name":"Proceedings of the 1st ACM SIGACT-SIGMOD symposium on Principles of database systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114499588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Session details: Session 4","authors":"Ratul Mahajan","doi":"10.1145/3262683","DOIUrl":"https://doi.org/10.1145/3262683","url":null,"abstract":"","PeriodicalId":126896,"journal":{"name":"Proceedings of the 1st ACM SIGACT-SIGMOD symposium on Principles of database systems","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124900899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We consider the problem of optimizing conjunctive queries in the presence of inclusion and functional dependencies. We show that the problem of containment (and hence those of equivalence and non-minimality) is in NP when either (a) there are no functional dependencies or (b) the set of dependencies is what we call key-based. These results assume that infinite databases are allowed. If only finite databases are allowed, new containments may arise, as we illustrate by an example. We also prove a "compactness" theorem that shows that no such examples can exist for case (b).
{"title":"Testing containment of conjunctive queries under functional and inclusion dependencies","authors":"David S. Johnson, Anthony C. Klug","doi":"10.1145/588111.588138","DOIUrl":"https://doi.org/10.1145/588111.588138","url":null,"abstract":"We consider the problem of optimizing conjunctive queries in the presence of inclusion and functional dependencies. We show that the problem of containment (and hence those of equivalence and non-minimality) is in NP when either (a) there are no functional dependencies or (b) the set of dependencies is what we call key-based. These results assume that infinite databases are allowed. If only finite databases are allowed, new containments may arise, as we illustrate by an example. We also prove a \"compactness\" theorem that shows that no such examples can exist for case (b).","PeriodicalId":126896,"journal":{"name":"Proceedings of the 1st ACM SIGACT-SIGMOD symposium on Principles of database systems","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123330604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
(This paper did not arrive in time to be published in these proceedings).
(这篇论文没有及时到达，未能在这些会议上发表)。
{"title":"The relational model of data and cylindrical algebras","authors":"T. Imielinski, W. Lipski","doi":"10.1145/588111.588139","DOIUrl":"https://doi.org/10.1145/588111.588139","url":null,"abstract":"(This paper did not arrive in time to be published in these proceedings).","PeriodicalId":126896,"journal":{"name":"Proceedings of the 1st ACM SIGACT-SIGMOD symposium on Principles of database systems","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1982-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126976245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：