W. W. McCune and L. J. Henschen. Maintaining state constraints in relational databases: A proof theoretic basis. Journal of the ACM 36 (1989), 46--68.  Home/Search   Document Not in Database   Summary   ACM   TOC   Related Articles   Check

....we could then modify the resulting transaction by applying simplification algorithms to wpc(T ; ff) thus recapturing many of the benefits of approaches based on validity checking. This is the fundamental idea underlying many algorithms for the automatic maintenance of integrity constraints [29, 21, 22, 31, 28]. Given the attractiveness of this approach to integrity maintenance, it is important to understand the tradeoffs involved in designing transaction and specification languages with respect to our ability to express weakest preconditions. In this paper, we will concentrate on the basic principles ....

....which is equivalent to the original one, and then 29 try to test its safety. As mentioned in the introduction, we are interested in transforming a verifiable transaction T into a safe transaction if wpc(T ; ff) then T else abort which will maintain ff as an invariant. As pointed out in [31, 21, 22, 28, 29], assuming that ff is always true, it may be possible to find a Delta, which is much simpler than wpc(T ; ff) such that ff ( Delta wpc(T ; ff) Using this we can transform T to if Delta then T else abort which is more efficient. We are interested in studying classes of transactions for ....

W. W. McCune and L. J. Henschen. Maintaining state constraints in relational databases: A proof theoretic basis. Journal of the ACM 36 (1989), 46--68.

....the instances of the constraint. Therefore, obtaining the simplified form for the constraint at update time leads to a significant increase in response time of updating operations performed to database states, particularly for transactions. This is a serious drawback of the simplification method [BM88, MH89]. The objective of our work presented in this report is to show that, for a given constraint W and an update that is to be performed to a relation R, it is not necessary to do all the steps of the method at update time. We do that by developing a representation that stores simplified instances of ....

W. W. McCune and L. J. Henschen. Maintaining State Constraints in Relational Databases: A Proof Theoretic Basis. Journal of the ACM, 36(1):69--91, 1989.

....we could then modify the resulting transaction by applying simplification algorithms to wpc(T ; ff) thus recapturing many of the benefits of approaches based on validity checking. This is the fundamental idea underlying many algorithms for the automatic maintenance of integrity constraints [26, 17, 18, 27, 25]. Given the attractiveness of this approach to integrity maintenance, it is important to understand the tradeoffs involved in designing transaction and specification languages with respect to our ability to express weakest preconditions. In this paper, we will concentrate on the basic principles ....

....transaction which is equivalent to the original one, and then try to test its safety. As mentioned in the introduction, we are interested in transforming a verifiable transaction T into a safe transaction if wpc(T ; ff) then T else abort which will maintain ff as an invariant. As pointed out in [27, 17, 18, 25, 26], assuming that ff is always true, it may be possible to find a Delta, which is much simpler than wpc(T ; ff) such that ff ( Delta wpc(T ; ff) Using this we can transform T to if Delta then T else abort which is more efficient. We are interested in studying classes of transactions for ....

W. W. McCune and L. J. Henschen. Maintaining state constraints in relational databases: A proof theoretic basis. Journal of the ACM 36 (1989), 46--68.

....specialization is the question whether necessary conditions like the one in our little example should be exploited, or not. Otherwise the methods proposed are essentially identical. The most significant contributions to constraint specialization in relational databases are [Nic82] BB82] and [MH89]. Let us now turn to constraint specialization in presence of rules. As mentioned earlier, implicit updates have to be considered as well, as they might indirectly lead to constraint violations. As an example assume these two general laws: Every member of some department is a properly ....

W. McCune and L. Henschen, "Maintaining state constraints in relational databases: A proof theoretic basis", Journal of the ACM, Vol. 36, No. 1, 1989

....database instance does not satisfy the set of constraints. Maintaining the database under updates so that it satisfies the set of constraints is called integrity enforcement (Nicolas 1982, Bernstein and Blaustein 1981, Hsu and Imielinski 1985, Bry et al. 1988, Ishakbeyoglu and Ozsoyoglu 1991, McCune and Henschen 1989, Ceri et al. 1994) The integrity enforcement is another important problem regarding the maintenance of integrity constraints. In this paper, our focus is on the problem of maintaining a non redundant and consistent set of database constraints under updates, and not on the integrity enforcement. ....

....the maintenance of integrity constraints. In the literature, several problems on the constraint maintenance have been discussed. One of them is the integrity enforcement problem (Nicolas 1982, Bernstein and Blaustein 1981, Hsu and Imielinski 1985, Bry et al. 1988, Ishakbeyoglu and Ozsoyoglu 1991, McCune and Henschen 1989, Ceri et al. 1994) that checks whether any of the constraints is invalidated with database updates in the form of tuple insertions deletions modifications.The second problem, which we also discuss here, is concerned with the consistency and redundancy in a constraint set when constraints are ....

McCune, W. W., Henschen, L. J., Maintaining State Constraints in Relational Databases: A Proof Theoretic Basis, Journal of the ACM, Vol. 36, No. 1, January 1989, pp. 46-68.

....databases. Nic82] is a fine presentation of the idea that consistency checking in non deductive databases may be simplified by knowing that a previous database state was consistent. Based on this work, Dec86, SK88, BDM88, Llo87, AIM88, ABI89, Oli91] extend these ideas to handle rules, whereas [MH89] still considers no deduction rules. These methods use a Prolog interpreter for checking the consistency. Globally speaking, they all work within the theorem proving framework which we characterized in section 2. Kuc91] also proposes using several phases of consistency checking, but rule ....

W. W. McCune and L. J. Henschen. Maintaining State Constraints in Relational Databases: A Proof Theoretic Basis. Journal of the ACM, 5(1):46--68, 1989.

....place a severe burden on database users to identify steps and breakpoints. Moreover, without additional knowledge about other transactions that are or may be in the system, the improvement in concurrency may be limited. Our method, inspired in part by work in deductive databases ( HN84] [MH89]) considers general database operations (read, write, modify) For a set of transactions to be executed concurrently, the method identifies the sets of conflicting tuples and arranges to have those tuples read into one or more buffers in high speed memory. The transactions themselves are then ....

....management model with semantics In this section we will give some definitions and sketches of the algorithms related to 1431 our model and a more systematic description of our model. 3.1 Database and Database Operations Definition 3. 1: We adopt the definition of a database state (DBT) from [MH89]. Definition 3.2: A Database operation in the new model is defined as a four tuple where OP is the type of the operation, i.e. DELETE, INSERT, etc. R is the relation the operation is to affect, and A is the set of attribute values affected by the operation. B is the buffer associated with this ....

William W. McCune and Lawrence J. Henschen "Maintaining State Constraints in Relational Database"; Journal of the Association for Computing Machinery; JACM Vol.36, No. 1, January 19 Page: 46-68; 1989.

Online articles have much greater impact   More about CiteSeer.IST   Add search form to your site   Submit documents   Feedback  

CiteSeer.IST - Copyright Penn State and NEC