K. Aberer and G. Fischer. Semantic query optimization for methods in object-oriented database systems. In IEEE International Conference Data Engineering, pages 70-79, 1995.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....would be useful for increasing the capability of a system to perform query optimization. Much work has been done to develop techniques for SQO in deductive and relational databases [3, 8, 10, 11, 13, 15] Recently, the issue of SQO in the context of object databases has also been considered [1, 12, 14, 16, 17]. We extend this work in the following ways: Our technique allows optimization of a much larger class of queries than considered before. In particular, queries with method application and structure constructors can be optimized. We use a uniform DATALOG representation for queries, schema and ....

K. Aberer and G. Fischer. Semantic query optimization for methods in object-oriented database systems. In Proc. IEEE International Conference Data Engineering, pages 70--79, 1995.

....in a separate rule. These rules are always valid given that they are specific to particular operators. Therefore they perform no inference nor conditional rewriting (Category (1) More recent work in the context of object models has looked at semantic optimization in the presence of methods. [1] considers semantic optimization over methods based on equivalences derived from method semantics. This semantics comes from the schema and is then translated by hand into rules that can be applied to expressions written in their algebra. As with [6] these rewrites are unconditional and there is ....

K. Aberer and G. Fischer. Semantic query optimization for methods in object-oriented database systems. In P. S. Yu and A. L. P. Chen, editors, Proceedings of the 11th International Conference on Data Engineering, pages 70--79, Taipei, Taiwan, 1995.

....Nested Queries Still to write about: ffl Kim [Kim82] ffl Ganski Wong [GW87] ffl Dayal [Day87] ffl Magic Sets [MP92, SPL96, SHP 96b] ffl Cluet and Moerkotte [CM95, CM93] ffl Steenhagen [SABd94] 7. 4 Semantic Optimization and Handling Foreign Functions ffl Zdonik [HZ80] ffl Aberer [AF95] ffl Chaudhuri and Kim [CS96, CS93] ffl Conjunctive Predicates [HS93, Hel94, LMS94] ffl Avoiding sorting [SSM96] ffl Semantics and Cost Estimation [NCN97] 7.5 Plan Languages, Partial Evaluation and Dynamic Optimization ffl Exodus Volcano [CDG 90, GM93] ffl OPA [DGK 91, Gra95] ffl ....

Karl Aberer and Gisela Fischer. Semantic query optimization for methods in objectoriented database systems. In P. S. Yu and A. L. P. Chen, editors, Proceedings of the 11th International Conference on Data Engineering, pages 70--79, Taipei, Taiwan, 1995.

....and databases requires flexible integration techniques for heterogeneous systems. The development of the AMOS system is geared towards the above mentioned concepts. These concepts are integrated within the existing object oriented DBMS VODAK ( Verteiltes Objektorientiertes DAtenbanKsystem 1 ) [2, 13, 12 20]. Our development efforts include: an extension of VODAK s data definition language to support temporal multimedia operations such as the simultaneous start of multiple media presentations [1] the integration of a storage management and object management component for continuous data ....

Aberer, K., Fischer, G.: "Semantic Query Optimization for Methods in Object-Oriented Database Systems ", Proc. of the 11th Int. Conf. on Data Engineering, Taipei, Taiwan, March 1995, pp. 70-79

....operators, cost functions for existing OODBS, and a broad range of storage structures implemented on top of existing object servers. Algebraic Rewriting. Many optimization systems for object oriented query languages transform a query into an expression of a logical (object) algebra (e.g. VODAK ([AF95]) Open OODB ( BMG93] as well as [CD92] Equivalences are defined on expressions of the algebra. The optimizer makes use of these equivalences by transforming expressions to find other algebraic representations of the query. Rule based optimizers heuristically prescribe direction and ....

K. Aberer and G. Fischer. Semantic Query Optimization for Methods in Object-Oriented Database Systems. In Proc. of the 11th ICDE, pages 70-- 79, Taipei, Taiwan, March 1995.

....and the evaluation precedence of reformulated queries. Yoon et al. 26] transform an object schema into a deductive database schema and use the residue technique of [4] to optimize a query. None of the papers reviewed above addresses the issue of SQO for queries with methods. Aberer and Fisher [1] argue that methods can be an excellent source of semantic information and show how information about method implementation can be used for SQO. All equivalences derived from methods are expressed by means of a query algebra. To complete the review, we mention two papers extending traditional SQO ....

....case, we can simply rewrite the original query substituting the method s name with its definition. After such rewriting, when the query does not refer to the method explicitly, the SQO technique described in Section 4 can be applied directly here. This type of query rewriting has been advocated in [1]. We note here that an optimization by means of method rewriting may require rather sophisticated heuristics. Methods are often accompanied by tools for their efficient evaluation. Suppose a query that contains such a method is first modified by replacing the method with its definition and then ....

Karl Aberer and Gisela Fischer. Semantic query optimization for methods in objectoriented database systems. In Proc. IEEE International Conference Data Engineering, pages 70--79, 1995.

....would be useful for increasing the capability of a system to perform query optimization. Much work has been done to develop techniques for SQO in deductive and relational databases [3, 8, 10, 11, 13, 15] Recently, the issue of SQO in the context of object databases has also been considered [1, 12, 14, 16, 17]. We extend this work in the followingways: Our technique allows optimization of a much larger class of queries than considered before. In particular, queries with method application and structure constructors can be optimized. We use a uniform DATALOG representation for queries, schema and ....

K. Aberer and G. Fischer. Semantic query optimization for methods in object-oriented database systems. In Proc. IEEE International Conference Data Engineering, pages 70--79, 1995.

....operators, cost functions for existing OODBS, and a broad range of storage structures implemented on top of existing object servers. Algebraic Rewriting. Many optimization systems for object oriented query languages transform a query into an expression of a logical (object) algebra (e.g. VODAK ( AF95] Open OODB ( BMG93] as well as [CD92] Equivalences are defined on expressions of the algebra. The optimizer makes use of these equivalences by transforming expressions to find other algebraic representations of the query. Rule based optimizers heuristically prescribe direction and ....

K. Aberer and G. Fischer. Semantic Query Optimization for Methods in Object-Oriented Database Systems. In Proc. of the 11th ICDE, pages 70--79, Taipei, Taiwan, March 1995.

....evaluated against user requirements. In addition to the new system internal components which are realized, in our first development step, we have extended VODAK s modelling language VML [23] to support multimedia datatypes. Furthermore, we also strive to extend our query language, called VQL [2], by concepts for querying multimedia data. 7 In the following, we first give an overview of the architecture of the AMOS system identifying components dedicated to the built in playout management service. Then we briefly discuss the main aspects of AMOS s integrated playout management ....

Aberer, K., Fischer, G.: "Semantic Query Optimization for Methods in Object-Oriented Database Systems", Proc. of the 11th Int. Conf. on Data Engineering, Taipei, Taiwan, March 1995, pp. 70-79

....technology in a much more efficient way, as compared to an application program. Furthermore, DBMSs allow for modifications of their content, even in multi user mode. We for our part have built a database application for structured documents [ABH94] based on the OODBMS VODAK [KAN94, K 94, AF95] If the database application is to administer documents of a particular type, the transition from the document type to the database schema seems to be very natural [CS87] Sacks Davis et al. say that the document type definition is the database schema [SDAMZ94] This does not exactly hold true ....

....in order to exploit the potential for optimization. The approach that the database or, more generally, the underlying system is furnished with more knowledge on the application semantics in order to fulfill its tasks in a more efficient way can be encountered in arbitrary contexts [M 93, AF95] In this particular setting, the application semantics is communicated by means of an SGML document. In other words, the database application framework has been made configurable. One may choose between different physical representations for elements (i.e. flat vs. non flat ) several ....

Karl Aberer and Gisela Fischer. Semantic query optimization for methods in object-oriented database systems. Proceedings of International Conference on Data Engineering 1995, 1995.

.... object oriented multimedia database management system developed at GMDIPSI [1, 33, 42, 28] The development of the AMOS system is driven by our experiences with real multimedia applications [32, 39, 40, 41] Its implementation is based on the object oriented database management system VODAK [22, 48, 2] which has also been developed at GMD IPSI. The integrated generic playout management service is provided by respective components of the AMOS client environment. The server supports the playout management by lower level functions, and synchronization constraints aware data delivery. In ....

....at GMDIPSI is the development of concepts needed for multimedia database management systems. As starting point, we employ the object oriented database management system VODAK which has been developed at GMD IPSI within Playout Management in Multimedia Database Systems 17 the past six years [22, 2, 48]. Our concepts are integrated with the VODAK system aiming at the development of an object oriented, and with respect to a client server architecture distributed multimedia database management system. Within this development process, the AMOS system (Figure 1.4) is already used in prototypes ....

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Aberer, K., Fischer, G.: "Semantic Query Optimization for Methods in Object Oriented Database Systems", Proc. of the 11th Int. Conf. on Data Engineering, Taipei, Taiwan, March 1995, pp. 70--79

.... management service [25] of our own distributed multimedia database management system AMOS (e.g. 1] 14] 16] 21] Several multimedia applications (e.g. 22] 23] 24] have already been developed by using AMOS which is based on the object oriented database management system VODAK (e.g. [2], 10] 20] The latter also has been developed at GMD IPSI. We will evaluate the performance and user acceptance of RAPM by respective empirical studies and simulation studies. ....

Aberer, K., Fischer, G.: "Semantic Query Optimization for Methods in Object-Oriented Database Systems", Proc. of the 11th Int. Conf. on Data Engineering, Taipei, Taiwan, March 1995, pp. 70-79

....approach results, to a certain degree, from the necessity to be able to modify individual document components. Techniques to optimize the evaluation of declarative queries are fundamental. The mechanisms provided by the VODAK Query Processor can be applied in this context in a reasonable way [AF94] The methods of the database schema are parameters of the query algebra on which the VODAK query language is based. The designer of the database schema has to specify equivalences between algebraic expressions correctly reflecting the semantics of the methods. Before evaluating the query the ....

Karl Aberer and Gisela Fischer. Semantic Query Optimization for Methods in Object-Oriented Database Systems. In Proceedings of ICDE-95 (to appear), 1994.

....a[i] The following routine match 2 will first traverse query path P to assign a state to each entry of a in the left to right order, and then perform the minimal cost matching in the right to left order. Initially, let a[i] state = 0 and a[i] cost = n before match 2 is called. 1 a[1].state # succ(0, A 1 ) 2 for i = 2 to n do a[i] state # succ(a[i 1] state, A i ) 3 for i = n downto 1 do 4 if a[i] state is accepting then 5 foreach index I q recognized at a[i] state do idx match(i, q) According to [12] the number of state transitions (including the failure state ....

....= B. strategy = I. subscript = 1 state = 3 strategy = F. state = 6 strategy = F. state = 7 strategy = F. state = 0 strategy = F. AB C D E F 1 backward traversal Indexed access by I 1 forward traversal 1 1 1 1 1 1 In Fig. 4, we see that the cheapest cost at entry a[1] is 3; by the routine output query strategy described in Section 12 the optimal query strategy in the right toleft order is (a) forward traversal on subpath P(6, 6) F, b) indexed access on subpath P(2, 5) B.C.D.E, and (c) backward traversal on subpath P(1, 1) A. Building the ....

ABERER, K., AND FISCHER, G. Semantic Query Optimization for Methods in Object -Oriented Database Systems. Proc. of the 11 ICDE, 1995.

....of transformation rules, we use the Volcano Optimizer Generator [11] to generate a query optimizer. Rules may have a condition part that specifies under which conditions the optimizer may apply these rule. We will introduce our optimizations as rules in PAT notation rather than at the Volcano level[1]. This is because PAT expressions are much easier to read, and the PAT level better reflects the optimizations we are aiming. 3 Using Knowledge on the DTD for Query Optimization In this article, we use knowledge on the DTD to identify more efficient evaluation strategies for queries posed ....

Karl Aberer and Gisela Fischer. Semantic Query Optimization for Methods in Object-Oriented Database Systems. In Proceedings of International Conference on Data Engineering, pages 70--79, 1995.

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AbF95 K. Aberer, G. Fischer (1995): "Semantic Query Optimization for Methods in Object-Oriented Database Systems", accepted for publication in Data Engineering 1995.

....Systems, 1997 Admissible Record Oriented Evaluation Plans for Declarative Updates 3 The Query Processing Model In general, declarative updates are formulated using a declarative language. We do not rely on a specific language, but assume that a declarative language like ODMG 93 OQL [4] or VQL [1][5] is used. The main requirement is that methods, including update methods, can be used in the formulation of queries and declarative updates, provided that the semantic correctness of the query update is given. We follow an algebraic approach with the distinction of a logical and a physical ....

....e.g. pushs selections down as far as possible, maps logical to physical algebra expressions using so called implementation rules, and chooses the cheapest physical expression as the evaluation plan. 3. 1 Logical Query Algebra The logical algebra we use in this paper has been introduced in [1]. It is not complete with regard to query languages like ODMG 93 OQL. For the sake of simplicity the expressiveness of the algebra is restricted to the class of declarative updates to which the results of this paper apply. The operators of the logical as well as the physical query algebra are ....

[Article contains additional citation context not shown here]

Aberer K, Fischer G. Semantic Query Optimization for Methods in Object-Oriented Database Systems. In: Proceedings of the 11th International Conference on Data Engineering. IEEE Computer Society Press, 1995, pp. 70-79.

.... language VQL of the OODBMS VODAK [21] We rely on the algebraic approach for query processing, and follow the distinction between a logical and a physical query algebra as introduced in [9] In this section, we will shortly present VQL and the logical algebra 7 (which have been introduced in [1]) introduce the operators of the physical algebra, and show how the latter are associated with concrete evaluation algorithms. Although a presentation of the model appears tedious, it is required for the subsequent, detailed analysis of update queries. 3.1 VQL VQL supports declarative access to ....

....results can have an influence on the choice of the appropriate physical operators for the final QEP. Therefore the conflict test should be integrated in the query optimization process. e.g. in VODAK we follow a rule based approach for query optimization based on the Volcano optimizer generator [1][9] By default, for VQL queries set oriented QEPs are generated. The conflict test can be integrated in the form of additional general implementation rules which, starting with the bottommost operator, map each logical operator lop in a logical algebra expression to the corresponding physical ....

K. Aberer, G. Fischer: "Semantic Query Optimization for Methods in Object-Oriented Database Systems", Proc. 11th ICDE, pp. 70--79, Taipeh, Taiwan, March 6--10, 1995.

No context found.

Aberer, K., Fischer, G.. Semantic Query Optimization for Methods in Object--Oriented Database Systems. In Proc. of 11th IEEE International Conference on Data Engineering, pp. 70--79, Taipei, Taiwan, March 6--10, 1995.

....query optimization. Solutions to this problem can be complemented with other optimization techniques, like those known from relational query optimization, or techniques, that consider other important aspects of the object oriented data model, like the semantic optimization of methods in queries [1]. The result of this paper is an efficient algorithm for determining the optimal evaluation strategy for a path query. In particular we exploit the fact that for path query optimization one can optimize each subpath separately, thus avoiding a combinatorial explosion in the search space. We ....

....first traverse query path P to assign a state to each entry of a in the left toright order, and then perform the minimal cost matching in the right to left order. 10 As for routine match 1 , let a[i] state = 0 and a[i] cost = # for 1 # i # n before match 2 is called. routine match 2 ( 1 a[1].state u succ(0, A 1 ) 2 for i = 2 to n do a[i] state u succ(a[i 1] state, A i ) 3 for i = n downto 1 do 4 if a[i] state is accepting then 5 foreach index I q recognized at a[i] state do idx match(i, q) 6 for k = i downto 1 do nonidx match(k, i) 7 8 According to [3] the number of ....

[Article contains additional citation context not shown here]

ABERER, K., AND FISCHER, G. Semantic Query Optimization for Methods in Object-Oriented Database Systems. Proc. of the 11 th ICDE, 1995.

....techniques. Another reason is that the semantics of methods is far more difficult to access and exploit for query processing. On the other hand considering method semantics for query optimization is an equally important and interesting issue for declarative object oriented query languages [3]. This fact was already recognized in the area of biomolecular databases [9] Only when methods semantic is considered in query processing the full power of methods can be exploited by queries. Within VODAK we have implemented an extensible query processing component [3] We are using an ....

....query languages [3] This fact was already recognized in the area of biomolecular databases [9] Only when methods semantic is considered in query processing the full power of methods can be exploited by queries. Within VODAK we have implemented an extensible query processing component [3]. We are using an algebraic and rule based approach to query optimization. The query optimizer is generated by using the Volcano optimizer generator [7] and we can generate application specific query optimization modules. We are currently experimenting with application specific optimization rules ....

Aberer, K., Fischer, G.: Semantic Query Optimization for Methods in Object-Oriented Database Systems. International Conference on Data Engineering, March 1995, Taipei, Taiwan.

.... of the VODAK hypermedia engine with the SGML (ISO 8879 1992) database schema developed at our institute (Aberer et al. 1994) the mapping to and integration of the linking architectural forms of the HyTime ISO standard (ISO IEC 10744 1992) and the tight integration of declarative VQL queries (Aberer and Fischer 1995) with the hypermedia engine. ACKNOWLEDGEMENTS We would like to thank Ajit Bapat for his contribution in implementing the presentation layer of the prototype and many valuable discussions for analyzing the SEPIA model. We also like to thank Gisela Fischer for her valuable comments on an earlier ....

K. Aberer and G. Fischer (1995) Semantic Query Optimization for Methods in Object-Oriented Database Systems. Proceedings of the 11th IEEE Conference on Data Engineering (ICDE '95), Taipei, Taiwan.

....routine match 2 will first traverse query path P to assign a state to each entry of a in the left to right order, and then perform the minimal cost matching in the right to left order. Initially, let a[i] state = 0 and a[i] cost = # for 1 # i # n before match 2 is called. routine match 2 ( 1 a[1].state u succ(0, A 1 ) 2 for i = 2 to n do a[i] state u succ(a[i 1] state, A i ) 3 for i = n downto 1 do 4 if a[i] state is accepting then 5 foreach index I q recognized at a[i] state do idx match(i, q) 6 for k = i downto 1 do nonidx match(k, i) 7 8 According to [12] the number of ....

....Fig. 3, applying match 2 ( yields the values at each entry shown in Fig. 4. 11 2 2 2 2 2 3 6 3 3 3 4 4 4 5 5 1 2 6 3 4 5 1 2 3 6 4 5 1 2 6 3 4 5 1 2 3 6 4 5 # 1 # # # # # # # # # # # # # # # # # # # (a) Table of cost fwd (b) Table of cost bwd Fig. 2 Pattern matching found by routine match 2 a[1]: state = 1 cost = 3 strategy = B. position = 1 a[2] state = 2 cost = 2 strategy = I. subscript = 1 a[3] state = 3 (accepting) cost = 4 strategy = F. position = 6 a[4] state = 6 cost = 3 strategy = F. position = 6 a[5] state = 7 (accepting) cost = 2 strategy = F. position = 6 a[6] ....

[Article contains additional citation context not shown here]

ABERER, K., AND FISCHER, G. Semantic Query Optimization for Methods in Object -Oriented Database Systems. Proc. of the 11 th ICDE, 1995.

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K. Aberer and G. Fischer. Semantic query optimization for methods in object-oriented database systems. In IEEE International Conference Data Engineering, pages 70-79, 1995.

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Aberer, K., and Fischer, G. 1995. Semantic Query Optimization for Methods in Object-Oriented Database Systems. In Proceedings of the Eleventh International Conference on Data Engineering, 70--79. Taipei, Taiwan.

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