Leonidas Fegaras, Chandrasekhar Srinivasan, Arvind Rajendran, and David Maier.  -db: an odmg-based object-oriented dbms. In Proceedings of the 2000.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....by other researchers. Section 6 concludes and points to future work. 2. TECHNICAL BACKGROUND This section introduces examples of ODL and OQL material used in the paper and brie y describes the query processing notions used in the solution, speci cally those implemented in OPTGEN [7, 8] and DB [9]. The ODMG standard for object databases [5] includes an object de nition language (ODL) and an object query language (OQL) Some familiarity with this model is assumed in the paper. ODL is used to declare a schema which de nes the valid application types. Figure 1 is an example ODL schema. ....

....the latter provide data values to the view. select struct(E:e.name, D:d.name) from e in Employees, d in Departments where e.dept = d; define worksFor( as select struct(E:e.name, D:d.name) from e in Employees, d in Departments where e. dept = d; Figure 2: OQL Query and View The DB system [9] implements a monoid comprehension calculus [8] and a monoid algebra over the ODMG object model (not including arrays and dictionaries) OQL queries in DB are rst translated into expressions in the calculus, normalized and then translated into monoid algebraic expressions. These can be ....

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L. Fegaras, C. Srinivasan, A. Rajendran, and D. Maier. -DB: An ODMG-Based Object-Oriented DBMS. In Proc. SIGMOD, page 583, 2000. SIGMOD Record 29(2), June 2000.

....But there are many heuristic cost based query optimizers that can handle hundreds of joins. One such system is GOO [8] which is a bottom up greedy algorithm that always performs the most pro table operations rst. Our framework will be implemented on top of the DB OODB management system [11], which uses GOO to optimize queries. To understand the diculty of the problem, consider the following XML OQL query: select info name e.name name , title b. title title from e in Instructors, b in document( book where b. author.name = e.name and ( exists a in ....

....on paper, the produced translations may contain many levels of nested queries, which can be overwhelmingly slow if they are interpreted as is. Hence, essential to the success of our framework is an OODB system that supports basic query unnesting, as is the case for the DB OODB management system [11]. The most common form of query unnesting that we expect any OODB system to be able to support is when the domain of a range variable is the result of another OQL query: select h 1 from . v in (select h 2 from v 1 in e 1 , vn in e n where p 2 ) where p 1 In that case, the query can ....

L. Fegaras, C. Srinivasan, A. Rajendran, and D. Maier. -DB: An ODMG-Based Object-Oriented DBMS. In Proceedings of the 2000 ACM SIGMOD International Conference on Management of Data, Dallas, Texas, page 583, May 2000.

....of nested queries, which can be overwhelmingly slow if they are interpreted as is. Hence, essential to the success of our framework is an OODB system that can support our translations e ectively. We have already built a fully functional, high performance OODB management system, called lambda DB [17], as part of a previous work. This system has a sophisticated query optimizer that unnests all nested queries, materializes path expressions into pointer joins, uses a cost based polynomial time heuristic for join ordering, and uses a rule based cost driven optimizer to generate physical plans. ....

....the same query via idrefs or content constraints. In addition, our framework is extendible, since it is rule based, and is easy to validate. 7 Implementation We have already implemented the schema less translation from XML OQL to OQL using the lambda DB object oriented database management system [17], which is built on top of the SHORE object storage system [6] This implementation is now part of the latest release (1.5) of lambda DB and is available at http: lambda.uta.edu lambda DB.html. The schema guided translations will require more substantial changes to the underlying OODB engine, ....

L. Fegaras, C. Srinivasan, A. Rajendran, and D. Maier. -DB: An ODMG-Based Object-Oriented DBMS. In Proceedings of the 2000 ACM SIGMOD International Conference on Management of Data, Dallas, Texas, page 583, May 2000.

....this query, but it is an easy task for an optimizer to transform this algebraic form into the form shown in Figure 12.D (by pulling the outer join up in the operator tree) 8. IMPLEMENTATION We have already built a prototype ODMG database management system, called DB , based on our framework [Fegaras et al. 2000]. Our system can handle most ODL declarations and can process most OQL query forms. The DB prototype is not ODMG compliant. Instead it supports its own C binding that provides a seamless integration between OQL and C with low impedance mismatch. It allows C variables to be used in queries ....

Fegaras, L., Srinivasan, C., Rajendran, A., and Maier, D. 2000. -db: An odmg-based object-oriented dbms. In Proceedings of the 2000 ACM SIGMOD International Conference on Management of Data, Dallas, Texas (May 2000), pp. 583.

.... this query, but it is an easy task for an optimizer to transform this algebraic form into the form shown in Figure 12.D (by pulling the outer join up in the operator tree) 8 Implementation We have already built a prototype ODMG database management system, called DB , based on our framework [FSRM00] Our system can handle most ODL declarations and can process most OQL query forms. DB is not ODMG compliant. Instead it supports its own C binding that provides a seamless integration between OQL and C with low impedance mismatch. It allows C variables to be used in queries and results ....

L. Fegaras, C. Srinivasan, A. Rajendran, and D. Maier. -DB: An ODMG-Based Object-Oriented DBMS. ACM SIGMOD International Conference on Management of Data, Dallas, Texas, page 583, May 2000.

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Leonidas Fegaras, Chandrasekhar Srinivasan, Arvind Rajendran, and David Maier.  -db: an odmg-based object-oriented dbms. In Proceedings of the 2000.

No context found.

L. Fegaras, C. Srinivasan, A. Rajendran, D. Maier, k-DB: An ODMG-Based Object-Oriented DBMS, in: Proc. SIGMOD, 2000, p. 583.

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