J. J. Lu, G. Moerkotte, J. Schue, and V. S. Subrahmanian. Efficient maintenance of materialized mediated views. In SIGMOD Conference 1995.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....how this condition guarantees the uniqueness of the set of derived authorizations. Finally, we address the problem of efficient access control by proposing a strategy, based on view materialization approaches. Our approach, which is based on a combination of the Dred [Gupta et al. 1993] and Stdel [Lu et al. 1995] approaches, avoids the high costs arising from the evaluation of the deductive rules when performing access control. Previous related work We first presented a proposal for an authorization model supporting authorizations with temporal intervals and a restricted set of derivation rules in ....

....and the TAB stratification without the need of recomputing them all upon the execution of administrative operations. The algorithms are based on techniques similar to those used for the maintenance of materialized views in constraint and deductive databases [Gupta et al. 1993; Lu et al. 1996; Lu et al. 1995]. These techniques can be successfully employed in our context due to the correspondence between a TAB and a constraint logic program, shown in subsection 3.3. All our algorithms (see [Ferrari 1998] for a detailed description) are based on both the Dred [Gupta et al. 1993] and the Stdel algorithm ....

[Article contains additional citation context not shown here]

Lu, J., Moerkotte, G., Schu, J., and Subrahmanian, V. 1995. Efficient maintenance of materialized mediated views. In ACM SIGMOD International Conference on Management of Data Proceedings (May 1995). ACM.

.... [BM95b] View indexing by means of pointer structures has been described in [Baek95] BM95a] BM95b] BM95c] JMR91] QW91] Rou82a] Rou82b] Rou91] RK91] Val87] The use and refreshment of materialized views has been de2 scribed in [BM90] CKPS95] GL95] GMR95] HK95] Han87] LMSS95] SJGP90] SR87] ZGMHW95] Incremental techniques has been described for active databases [CSL 90] CW91] HCKW90] Han92] RCBB89] WDSY91] for deductive databases [GMS93] and for temporal databases [BM95c] JMR91] McK88] However, we are not aware of existing incremental ....

J.J. Lu, G. Moerkotte, J. Schue, and V.S. Subrahmanian. Efficient Maintenance of Materialized Mediated Views. In Proceedings of the 1995 ACM SIGMOD International Conference on Management of Data, San Jose, California, USA, pages 340--351, 1995.

....the materialized view from scratch after an update to the source data. However, because of the size and complexity of the materialized views, this approach is normally too inefficient to be feasible in practice. A more efficient approach is to maintain the materialised views incrementally [9, 7, 17, 6, 2, 19, 18, 20, 5, 3, 15, 22, 14, 12, 13]. In this approach, the updated materialised view is computed from the update, the current materialized view and possibly some source data. For example, let the view V be defined in the flat relational model (using set semantics) as V = r(X; Y ) s(Y; Z) For an insertion ffi r to r, the ....

J. Lu, G. Morekette, J. Schu, and V. Subrahmanian. Efficient maintenance of materialized mediated views. In ACM SIGMOD Conference, pages 340--351, 1995.

....updates# ffl Workflow. 1 Mediation supports semantic integration of databases from the read only view of information sources that reside at different sites. Interesting proposals for mediating database systems can be found in the literature, both for relational and logic deductive databases [34,37, 30, 5, 11]. All of this proposal considers only the first kind of mediation, the one without updating capabilities. With respect to integration for read only access to information sources, two approaches can be found in the literature to support view integration, one is called the virtual approach and the ....

J. J. Lu, G. Moerkotte, J. Schue, and V. S. Subrahmanian. Efficient maintenance of materialized mediated views. In SIGMOD Conference 1995, pages 340--351, 1995.

....there exist many constructs native to existing DBMSs that can be utilizized. For example, there has been much work done involving the addition of rules to database systems [CW92, S 95, SJGP90, HKBBS92, HW92] particularly in support of constraints [CW93, GJ91] and views [DH84, BLT86, GMS93, LMSS95, Mot87] Similarly, schema integration [BLN86, SM89] has been studied extensively. Once we have the ability to add a new type of database system to an alliance, much of the conversion that needs to be done (e.g. schema translation, query translation, etc. is not as huge a task as it may have ....

J.J. Lu, G. Moerkotte, J. Schue, and V.S. Subrahmanian. Efficient maintenance of materialized mediated views. In Proc. ACM SIGMOD Symp. on the Management of Data, pages 340--351, 1995.

....we may access multiple heterogeneous data sources. Before proceeding to this definition, we need to introduce some syntactic assumptions. The content of Section 2.1 is not new work. It builds upon a previous effort called HERMES by one of the authors on heterogeneous data and software integration [1, 20, 61, 60, 63]. The reader familiar with that syntax may skip this section. Suppose we consider a body S = T S ; F S ) of software code. Given any type 2 T S , we will assume that there is a set V ar( of variable symbols ranging over . If X 2 V ar( is such a variable symbol, and if is a complex ....

....databases as well. It is closely related to the HERMES effort. HERMES used minimalistic versions of logic to integrate data and software, while SIMS used a somewhat richer language. As a consequence, HERMES was able to take advantage of very efficient caching and query optimization methods [60, 1], but may have not been able to easily express some of the more sophisticated reasoning tasks desired by the authors of SIMS. Other important later directions on mediation include the InfoSleuth effort [13] at MCC. 7 Conclusions and Future Work In this paper, we have argued the following two ....

J. Lu, G. Moerkotte, J. Schue, and V. Subrahmanian. Efficient Maintenance of Materialized Mediated Views. In M. Carey and D. A. Schneider, editors, ACM SIGMOD Conf. on Management of Data, pages 340--351, San Jose, CA, May 1995.

....recent example is group awareness in cooperative engineering: designers working on a certain aspect of a product should be made aware of concurrent changes in requirements or by other designers. Yet another step towards the open electronic Internet market is change propagation in data warehousing [23, 10]. Traditional database systems leave the responsibility of keeping informed about updates largely to the client. Since the client cannot know what changes have happened, it must repeat queries in a polling mode. Even worse, although the server must re compute the whole query each time, the client ....

....Some special cases allow for faster counting algorithms, some complex cases (e.g. duplicates) require additional treatment. While most formal results have been developed in a Datalog context, results have also been transfered to active relational databases [2] multi databases and data warehouses [23, 10]. 3 Incremental Maintenance of Materialized Views: A Declarative Solution In this section, we present the first group of algorithms which assumes that views are in fact materialized not only in the external client but also in the server. Our algorithm (section 3.1) follows the three step ....

J.J. Lu, Moerkotte G., J. Schue, and V.S. Subrahmanian. Efficient maintenance of materialized mediated views. In ACM SIGMOD Intl. Conf. on Management of Data, pages 340--351, 1995.

....using materialized views. They present a concurrency control algorithm to ensure that queries to remote databases are correctly handled while doing view maintenance at the warehouse. The concurrency control problem they solve only appears if view maintenance requires access to base relations. [LMSS95] present a very different model of integration. They consider views defined using some remote and some local relations. They materialize the view only partially, without accessing the remote relation, by retaining a reference to the remote relation as a constraint in the view tuples. This model ....

J. Lu, G. Moerkotte, J. Schu, and V. S. Subrahmanian. Efficient maintenance of materialized mediated views. In Carey and Schneider [CS95].

....we may access multiple heterogeneous data sources. Before proceeding to this definition, we need to introduce some syntactic assumptions. The content of Section 3.1 is not new work. It builds upon a previous effort called HERMES by one of the authors on heterogeneous data and software integration [1, 19, 74, 73, 76]. The reader familiar with that syntax may skip this section. Suppose we consider a body S = T S ; F S ) of software code. Given any type 2 T S , we will assume that there is a set V ar( of variable symbols ranging over . If X 2 V ar( is such a variable symbol, and if is a complex ....

....databases as well. It is closely related to the HERMES effort. HERMES used minimalistic versions of logic to integrate data and software, while SIMS used a somewhat richer language. As a consequence, HERMES was able to take advantage of very efficient caching and query optimization methods [73, 1], but may have not been able to easily express some of the more sophisticated reasoning tasks desired by the authors of SIMS. Other important later directions on mediation include the InfoSleuth effort [12] system, at MCC. 12 Conclusions and Future Work In this paper, we have argued the following ....

J. Lu, G. Moerkotte, J. Schue, and V.S. Subrahmanian. Efficient Maintenance of Materialized Mediated Views. In: Proc. 1995 ACM SIGMOD Conf. on Management of Data, San Jose, CA, May 1995.

....assessment service. transaction management = assuring that temporal consistency of databases is not compromised by updates. value = content metric in customer model, as quality, relevance, up to dateness, cost. view = subset of a database constrained to a domain, and restructured as required [LuMSS:95] view object = data object constructed from a database view and model [BarsalouW: 89] virtual data = data represented by references and procedures. warehouse = a database containing or providing access to selected, abstracted, and integrated data from multiple resources; typically redundant ....

James J. Lu, Guido Moerkotte, Joachime Schue, and V.S. Subrahmanian: "Efficient Maintenance of Materialized Mediated Views"; Proc. International Conference on Management of Data (Sigmod 95), ACM, 1995.

....statement. As changes are made to the data sources, the warehouse views must be updated to reflect the changed state of the data sources. The views either can be recomputed from scratch, or incremental maintenance techniques [BC79, SI84, RK86, BLT86, Han87, SP89, QW91, Qua96, CW91, GMS93, GL95, LMSS95, ZGHW95] can be used to calculate the changes to the views due to the source changes. Using the incremental maintenance approach, the warehouse can be updated either immediately as soon as a change from a source is received, or the update can be deferred until a time when a large batch of ....

J. Lu, G. Moerkotte, J. Schu, and V. Subrahmanian. Efficient maintenance of materialized mediated views. In Carey and Schneider [CS95].

....how this condition guarantees the uniqueness of the set of derived authorizations. Finally, we address the problem of efficient access control by proposing a strategy based on view materialization approaches. Our approach, which is based on a combination of the Dred [Gupta et al. 1993] and Stdel [Lu et al. 1995] approaches, avoids the high costs arising from the evaluation of the deductive rules when performing access control. Previous related work We first presented a proposal for an authorization model supporting authorizations with temporal intervals and a restricted set of derivation rules in ....

....TABEXT and the TAB stratification without the need of recomputing them upon the execution of administrative operations. The algorithms are based on techniques similar to those used for the maintenance of materialized views in constraint and deductive databases [Gupta et al. 1993; Lu et al. 1996; Lu et al. 1995]. These techniques can be successfully employed in our context due to the correspondence between a TAB and a constraint logic program, shown in subsection 3.3. All our algorithms (see [Ferrari 1998] for a detailed description) are based on both the Dred [Gupta et al. 1993] and the Stdel An ....

[Article contains additional citation context not shown here]

Lu, J., Moerkotte, G., Schu, J., and Subrahmanian, V. 1995. Efficient maintenance of materialized mediated views. In ACM SIGMOD International Conference on Management of Data Proceedings (May 1995). ACM.

....tuples using outer joins and a match operator is done in [GJM94] while more general matching conditions are discussed in [ZHKF95] The matching conditions of [ZHKF95] may be expensive to compute. By materializing the composed objects, in part or fully, the objects can be used inexpensivelym. LMSS95b] presents another model of data integration. They consider views defined using some remote and some local relations. They materialize the view partially, without accessing the remote relation, by retaining a reference to the remote relation as a constraint in the view tuples. The model needs ....

J. Lu, G. Moerkotte, J. Schu, and V. S. Subrahmanian. Efficient maintenance of materialized mediated views. In SIGMOD 1995, pages 340--351.

.... view, and to support queries against the view by query decomposition, query shipping, and integration of query results [3] 22] 25] More recently, the use of materialization has been gaining increasing attention in connection with supporting both single source and integrated views [2] 26] [23], 29] There are a variety of situations under which materialization is preferable to the virtual approach, e.g. cases where network connectivity is unreliable, where response time to queries is critical, or where it is cheaper to materialize and incrementally maintain intricate relationships ....

J.J. Lu, G. Moerkotte, J. Schue, and V.S. Subrahmanian. Efficient maintenance of materialized mediated views. In Proc. ACM SIGMOD Symp. on the Management of Data, pages 340--351, 1995.

No context found.

J. Lu, G. Moerkotte, J. Schu, and V.S. Subrahmanian. Efficient maintenance of materialized mediated views. In Proceedings of the ACM SIGMOD Annual Conference, San Jose, CA, May 1995. ACM Press.

....we may access multiple heterogeneous data sources. Before proceeding to this definition, we need to introduce some syntactic assumptions. The content of Section 2.1 is not new work. It builds upon a previous effort called HERMES by one of the authors on heterogeneous data and software integration [1, 20, 61, 60, 63]. The reader familiar with that syntax may skip this section. Suppose we consider a body S = T S ; F S ) of software code. Given any type 2 T S , we will assume that there is a set V ar( of variable symbols ranging over . If X 2 V ar( is such a variable symbol, and if is a complex record ....

....databases as well. It is closely related to the HERMES effort. HERMES used minimalistic versions of logic to integrate data and software, while SIMS used a somewhat richer language. As a consequence, HERMES was able to take advantage of very efficient caching and query optimization methods [60, 1], but may have not been able to easily express some of the more sophisticated reasoning tasks desired by the authors of SIMS. Other important later directions on mediation include the InfoSleuth effort [13] at MCC. 7 Conclusions and Future Work In this paper, we have argued the following two ....

J. Lu, G. Moerkotte, J. Schue, and V. Subrahmanian. Efficient Maintenance of Materialized Mediated Views. In M. Carey and D. A. Schneider, editors, ACM SIGMOD Conf. on Management of Data, pages 340--351, San Jose, CA, May 1995.

....equivalence among objects, but up to now no graphical tool modeling the dataflow in mediatory information systems has been made available. Our model has several other applications: It provides a natural and simple mechanism for maintaining mediated views very different from algorithms such as [16]. Once the rules defining a view have been transformed into a Petri net, base relation updates and view redefinitions can be simply modeled by the addition or deletion of the corresponding places and transitions from the network. The well understood relationship of Petri nets and concurrency ....

....N Multiple information systems and uncertainty P(1 : n) Omega N Time, multiple information systems and uncertainty T Omega P(1 : n) Omega N Table 2: Selected examples of (product)lattices 3.1. 2 Integrating external Information Sources The following description is taken from [16] and [17] We add a constraint part to annotated clauses to enrich the expressiveness of GAPs and to provide a way to access external information systems. Given a domain set D of objects that we wish to reason about, a set F of functions that are used to manipulate the objects and a set R of ....

[Article contains additional citation context not shown here]

Jim Lu, Guido Moerkotte, Joachim Schu, V.S. Subrahmanian. Efficient Maintenance of Materialized Mediated Views. Accepted for ACM SIGMOD, 1995 15

....; A n : where A; A 1 ; A n are atoms, and D 1 ; Dm are DCA atoms. Note that for simplicity, we restrict constraints to DCA atoms of the form described above. This does not however, detract from the generality of the techniques described in the paper It has been shown in [22] that all the types of constraints considered by Kanellakis et al. can be captured within this framework (Lu, Nerode, and Subrahmanian present further details [21] Given any mediator M that integrates information from domains d 1 ; d n , we use the notation (M; fd 1 ; d n g) j= ....

.... ; i) is true and such that (TR m (M) fd 1 ; d k g) j= 8)A (i) The above theorem has the following important impact HERMES currently computes the j= relation in a sound and complete manner, using a compiler that pre computes a materialized mediated view (cache) as described in [22], and then using this cache for query processing instead of the rules, unless there is no option but to use the mediator rules. Various intelligent caching techniques to support this kind of query processing [2] By having the ability to translate the secure query processing problem into one that ....

J. Lu, G. Moerkotte, J. Schue and V.S. Subrahmanian. (1995) Efficient Maintenance of Materialized Mediated Views, Proc. 1995 ACM SIGMOD Conf. on Management of Data, to appear, May 1995.

....23, 25, 26] These papers show how views (and their materializations) may be defined for different kinds of databases such as relational DBMSs, object oriented DBMSs, and object relational systems. However, it is only recently that materialized views were studied in the context of mediated systems [19]. Consequently, very little work has been done on how to effectively use such materialized mediated views to effectively process queries [33, 34, 39, 40] A materialized mediated view may be viewed as a domain cache and hence, all the algorithms in this paper deal with how to effectively use such ....

J. Lu, G. Moerkotte, J. Schue, V.S. Subrahmanian. (1995) Efficient Maintenance of Materialized Mediated Views, Proc. 1995 ACM SIGMOD Conf. on Management of Data, San Jose, CA, May 1995.

....occur in one or more of the base relations upon which this view is defined. In such cases, the materialized view must be updated to incorporate the changes that occur in the base relation this is the problem of View Maintenance. View Maintenance is a subject that has been studied by many [1, 3, 5, 6, 8, 9, 10, 11, 15, 16, 17, 18, 21, 22, 25, 26, 27, 28, 29, 30, 31, 32, 33, 35, 23]. Every view maintenance technique in existence depends fundamentally upon the following key parameters: Computer Science Dept. Bucknell University, Lewisburg, PA 17837, USA. jameslu bucknell.edu. Supported by the NSF under Grant CCR9225037. y Institut fur Informatik, Universitat Freiburg. ....

....SQL query or in terms of a Datalog query of the form A B 1 ; B n . In general, there are many different ways of specifying a view. ffl How is the materialized view stored Most often, a materialized view is stored as a set of relations; however, there are differences for example, in [23] materialized views are sets of constrained tuples. ffl What kinds of updates are allowed Several techniques only allow updates (insertions deletions) to base relations. However, it is often the case that derived relations (views) are defined in terms of other derived relations. Under these ....

[Article contains additional citation context not shown here]

J. Lu, G. Moerkotte, J. Schu and V.S. Subrahmanian. (1995) Efficient Maintenance of Materialized Mediated Views, Proceedings of the ACM SIGMOD Annual Conference, May 1995, San Jose, CA.

....has seen it. In traditional databases, view maintenance has been studied extensively in the context of relational databases [3, 15] deductive databases [20] and object oriented databases [21, 6] More recently, attempts have been made to build views on top of heterogeneous information sources [7, 29] leading to the emerging area of data warehousing. One of the fundamental problems that arises when materialized views are created is that the base relations on top of which these views are defined may be updated from time to time. This in turn may cause the answer to the query defining the view ....

J. Lu, G. Moerkotte, J. Schue, and V.S. Subrahmanian. Efficient Maintenance of Materialized Mediated Views, Proc. 1995 ACM SIGMOD Conf. on Management of Data, San Jose, CA, May 1995.

....1 ; An : where A; A 1 ; An are atoms, and D 1 ; Dm are DCA atoms. Note that for simplicity, we restrict constraints to DCA atoms of the form described above. This does not however, detract from the generality of the techniques described in the paper It has been shown in [11] that all the types of constraints considered by Kanellakis et al. can be captured within this framework (Lu, Nerode, and Subrahmanian present further details [10] Given any mediator M that integrates information from domains d 1 ; dn , we use the notation (M; fd 1 ; dng) j= A ....

.... ; i) is true and such that (TR m (M ) fd 1 ; d k g) j= 8)A (i) The above theorem has the following important impact HERMES currently computes the j= relation in a sound and complete manner, using a compiler that pre computes a materialized mediated view (cache) as described in [11], and then using this cache for query processing instead of the rules, unless there is no option but to use the mediator rules. Various intelligent caching techniques to support this kind of query processing [2] By having the ability to translate the secure query processing problem into one that ....

J. Lu, G. Moerkotte, J. Schue and V.S. Subrahmanian. (1995) Efficient Maintenance of Materialized Mediated Views, Proc. 1995 ACM SIGMOD Conf. on Management of Data, to appear, May 1995.

....flexibility in allowing the language L to vary is particularly useful, as in most real world applications, we expect different agents to reason differently. 6 Section 3.2 the heart of this paper contains the key new technical contributions. 7 The contents of this section are not new, see [7, 1, 24, 21, 22] for more details. 8 This assumption is consistent with all well known object based software interoperability frameworks such as CORBA ODE [12] and ODMG s ODL [10] An agent is built on top of S by adding: 1) a service description (in a special language described in [3] which describes the ....

....A service description consists of a service name, a set of mandatory inputs required to use that service, a set of inputs (not required) that may be provided, and a set of outputs generated by the agent providing that service. A service 10 The current implementation, based on our HERMES platform [24, 7, 21, 8, 1], supports Ingres, Dbase, Paradox, packages for face recognition, nonlinear planning and terrain reasoning, operations research software, a GIS and a text indexing system. 11 Further important issues relate to access control and authentication protocols [23] that we do not address here for space ....

J. Lu, G. Moerkotte, J. Schue, and V.S. Subrahmanian. Efficient Maintenance of Materialized Mediated Views, in: Proc. 1995 ACM SIGMOD Conf. on Management of Data, San Jose, CA, May 1995.

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J. J. Lu, G. Moerkotte, J. Schue, and V. S. Subrahmanian. Efficient maintenance of materialized mediated views. In SIGMOD Conference 1995.

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J. Lu, G. Morekette, J. Schu, and V. Subrahmanian. Efficient maintenance of materialized mediated views. In ACM SIGMOD Conference, pages 340--351, 1995.

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J. Lu et al., "Efficient Maintenance of Materialized Mediated Views," Proc. 1995 ACM SIGMOD Conf. Management of Data, ACM Press, 1995.

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J.J. Lu, G. Moerkotte, J. Schue and V.S. Subrahmanian, "Efficient Maintenance of Materialized Mediated Views", SIGMOD '95.

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J. Lu, G. Moerkotte, J. Schu, and V. Subrahmanian. Efficient maintenance of materialized mediated views. In SIGMOD, 1995.

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