Johann Christoph Freytag. A Rule-Based View of Query Optimization. Proceedings of the 1987.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....and algorithms is easy. A query optimization system that o ers a xed search strategy is always a rulebased system. It often implements a rule rewriter to perform equivalent transformation on the query expressions. Representatives of this kind of system include: the System R style Optimizer [15], Starburst project [16] 31] the Exodus Optimizer Generator [7] and the Volcano Optimizer Generator [8] The system R style Optimizer designs sets of rules to translate a query into a physical plan. One set of them is to convert the query into an algebraic tree. Other sets are used to generate ....

Johann Christoph Freytag. A Rule-Based View of Query Optimization. Proceedings of the 1987.

....we describe the thesis work in the coming sections. 15 3 KOLA: Ensuring the Correctness of Optimizers This section motivates and presents KOLA, a novel combinator based (variable free) representation and algebra of queries. KOLA is a query representation for rule based optimizers [CDG 90, Fre87] optimizers that express query transformations incrementally in terms of rules. Though intended to make optimizers extensible, rule based optimizers are also well suited for expressing algebraic transformations in a way that permits reasoning about their correctness. 3.1 The Need for a ....

....[BTBW92] ffl Complexity of Translations [JRSB85] 7.2 Comparing COKO with Query Rewrites of Rule Based Optimizers Many rule based systems (e.g. Loh88] FMS93] use rules to map algebraic operators to plan level implementations. This was the intended purpose of rules when first proposed ( Fre87] and also characterizes one of the two kinds of rules used in Exodus [CDG 90] and Starburst [HFLP89] KOLA and COKO express query rewrites (i.e. query to query mappings) rather than query toplan mappings, and hence are incomparable to the rules of these systems. Below, we describe how ....

Johann Christoph Freytag. A rule-based view of query optimization. In Umeshwar Dayal and Irv Traiger, editors, Proceedings of the SIGMOD International Conference on Management of Data, pages 173--180, San Francisco, California, May 1987. ACM Special Interest Group on Management of Data, ACM Press.

....CA 94065, USA difficult to change. Customizability of such optimizers is almost impossible without an enormous effort by the database implementor (DBI) This difficulty has lead to the development of rule based query optimizers, whose primary purpose is to achieve query optimizer extensibility [9, 10, 12, 13]. The basic idea is that the actions of a query optimizer are defined as a set of rewrite rules that progressively optimize expressions which define how queries can be evaluated. From our experience, the rule sets of such optimizers are rather brittle. If a new feature (e.g. retrieval or join ....

Johann Christoph Freytag. A rule-based view of query optimization. In Proceedings1987 ACM SIGMOD International Conference on Management of Data, pages 173--180, San Francisco, May 1987.

....implemented using this framework, the addition of new algorithms and operators is easy. Most optimizers that allow extensibility of the query algebra employ some form of a rule based system that uses rewrite rules to describe transformations that can be performed to optimize a query expression [Fre87, Gra87, PHH92, FG91] These systems usually offer a more or less fixed search strategy that is difficult to modify or extend. Freytag [Fre87] describes an architecture in which the translation of a query into an executable plan is completely based on rules. He describes a System R style optimizer ....

....algebra employ some form of a rule based system that uses rewrite rules to describe transformations that can be performed to optimize a query expression [Fre87, Gra87, PHH92, FG91] These systems usually offer a more or less fixed search strategy that is difficult to modify or extend. Freytag [Fre87] describes an architecture in which the translation of a query into an executable plan is completely based on rules. He describes a System R style optimizer that can be built using various sets of rules. One set of rules is used to convert the query into an algebraic tree. Other sets of rules are ....

Johann Christoph Freytag. "A Rule-Based View of Query Optimization". In Proceedings of the 1987 ACM-SIGMOD Conference, San Francisco, California, May 1987.

....The extensibility in this system derives from the ability to model extensions in the path model, and the generality of the optimization stages. Many subsequent systems use rewrite rules to describe the transformations that can be performed to optimize a query expression [45, 54, 115, 137] Freytag [48] claimed that rules are sufficient for translating a user query into a query evaluation plan and, to illustrate, showed how access paths and join orders in System R optimization could be generated using transformation rules. He illustrated an optimizer that successively applied different sets of ....

Johann Cristoph Freytag. A Rule-Based View of Query Optimization. In SIGMOD Proceedings, pages 173--180, May 1987.

....are used to store and retrieve data are hard wired and are rather difficult to change. The need to have extensible database systems, and in turn extensible optimizers, has long been recognized in systems like EXODUS [17] Starburst [43] Genesis [4] and Postgres [49] Rule based query optimizers [25, 28, 30, 31, 33, 36] are among the major conceptual advances that have been proposed to deal with query optimizer extensibility. A primary advantage of rule based optimizers over traditional ones is the ability to introduce new functionality in a query algebra without changing the optimization algorithm. We will ....

....not done until all rules are applied. In other words, the rewrite rules of Starburst are purely syntactic transformations of one query representation into another. Thus, all operator trees are subjected to all applicable rules before costs are computed and the search space can be pruned. Freytag [25] describes a rule based query optimizer similar to Starburst. The rules are based on LISP like representations of access plans. The rules themselves are recursively defined on smaller expressions (operator trees) Although several expressions can contain a common sub expression, Freytag doesn t ....

Johann Christoph Freytag. A rule-based view of query optimization. In Proceedings 1987 ACM SIGMOD International Conference on Management of Data, pages 173-- 180, San Francisco, May 1987.

.... database systems, and in turn extensible optimizers, has long been recognized in systems like Genesis [1] EXODUS [9] Starburst [10] and Postgres [12] Rule based query optimizers are among the major conceptual advances that have been proposed to deal with query optimizer extensibility [6, 7, 9, 10]. The extensibility translates into the ability to incorporate new operators, algorithms, cost models, or search strategies without changing the optimization algorithm. In this paper, we describe an algebraic framework called Prairie for specifying rules in a rule based query optimizer. Prairie ....

....selects algorithms for each operator in the operator tree that is obtained after rewriting. The disadvantage of separating the query rewrite and the optimization phases is that pruning of the search space is not possible during query rewrite, since the rewrite phase is non cost based. Freytag [6] describes a rule based query optimizer similar to Starburst. The rules are based on LISP like representations of access plans. The rules themselves are recursively defined on smaller expressions (operator trees) Although several expressions can contain a common sub expression, Freytag doesn t ....

Johann Christoph Freytag. A rule-based view of query optimization. In Proceedings 1987 ACM SIGMOD International Conference on Management of Data, pages 173--180, San Francisco, May 1987.

....form, and then a set of rules that maps algebra operators to physical operators is used to generate a plan. The key components in a rule based optimizer are the language for describing rules, the search strategy, and the rules themselves. Rule based optimization was first suggested by Freytag[34, 36, 35]. His initial proposal calls for two layers, where the first layer rewrites the Lisp like intermediate representation of the query. The rewriting phase does not distinguish between source and physical rules, although it possesses both. The second layer translates the intermediate representation ....

Johann Christoph Freytag. A rule-based view of query optimization. In Dayal and Traiger

....using this design, the addition of new algorithms and operators to the system is easy. Most optimizers that allow extensibility of the query algebra propose some form of a rule based system that uses rewrite rules to describe transformations that can be performed to optimize a query expression [Fre87, Gra87, PHH92, FG91] These systems usually offer a more or less fixed search strategy that is difficult to modify or extend. Freytag [Fre87] describes an architecture in which the translation of a query into an executable plan is completely based on rules. He describes a System R style optimizer ....

....algebra propose some form of a rule based system that uses rewrite rules to describe transformations that can be performed to optimize a query expression [Fre87, Gra87, PHH92, FG91] These systems usually offer a more or less fixed search strategy that is difficult to modify or extend. Freytag [Fre87] describes an architecture in which the translation of a query into an executable plan is completely based on rules. He describes a System R style optimizer that can be built using various sets of rules. One set of rules is used to convert the query into an algebraic tree. Other sets of rules are ....

Johann Christoph Freytag. "A Rule-Based View of Query Optimization". In Proceedings of the 1987 ACM-SIGMOD Conference, San Francisco, Californai, May 1987.

.... extensible database systems, and in turn extensible optimizers, has long been recognized in systems like Genesis [1] EXODUS [3] Starburst [15] and Postgres [18] Rule based query optimizers are among the major conceptual advances that have been proposed to deal with query optimizer extensibility [6 8, 10, 11, 13]. The extensibility translates into the ability to incorporate new operators, algorithms, cost models, or search strategies without changing the optimization algorithm. In this paper, we describe an algebraic framework called Prairie for specifying rules in a query optimizer. Prairie is similar to ....

....selects algorithms for each operator in the operator tree that is obtained after rewriting. The disadvantage of separating the query rewrite and the optimization phases is that pruning of the search space is not possible during query rewrite, since the rewrite phase is non cost based. Freytag [6] describes a rule based query optimizer similar to Starburst. The rules are based on LISP like representations of access plans. The rules themselves are recursively defined on smaller expressions (operator trees) Although several expressions can contain a common sub expression, Freytag doesn t ....

Johann ChristophFreytag. A rule-based view of query optimization. In Proceedings1987 ACM SIGMOD International Conference on Management of Data, pages 173--180, San Francisco, May 1987.

No context found.

Johann Christoph Freytag. A rule based view of query optimization. In Umeshwar Dayal and Irv Traiger, editors, Proceedings of ACM-SIGMOD International Conference on Management of Data, pages 173--180, San Francisco, May 1987.

No context found.

Johann Christoph Freytag. A rule-based view of query optimization. In Proceedings ACM-SIGMOD, pages 173--180. ACM, 1987.

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