R.S.G. Lanzelotte, P. Valduriez, and M. Zait. Optimization of object-oriented recursive queries using cost-controlled strategies. In Proc. ACM SIGMOD, 1992.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....database about whether certain preconditions for the triggering action are true. One can also use the declarative langauge to define simple methods that can be expressed as views. 3 An Example We illustrate several of the features of Noodle using an example of a composer database originally from [LVZ92]. The database has four classes, namely person, composer , composition, and instrument , related as shown in Figure 2. All person objects have a name attribute and a birthdate attribute. The class person has an associated method age; age(object = p; result = A) gives the current age of the person ....

....= composer) and a definition of the relation composer(member : object ; name : string; birthdate : date ; age : int ; master : composer ; works : set) If there was a subclass set of compositions of set , then this would be a better type for the works attribute. 3 We now express the queries of [LVZ92] in Noodle. The query Find the title of works by Bach including a harpsichord and flute can be expressed as: Q1) Y : composer (member = V; name = Bach ; works = W ) W (element = X) X(title = Y; instruments = Z) Z(element = harpsichord ) Z(element = flute ) The view ....

Rosana S. G. Lanzelotte, Patrick Valduriez, and Mohamed Zait. Optimization of object-oriented recursive queries using cost-controlled strategies. In Proceedings of ACM SIGMOD 1992 International Conference on Management of Data, pages 256--265, San Diego, CA, June 2-5 1992.

....[M91] and VERSANT [GD91] have introduced SQL based query languages. An improved query model was developed for ORION [K90a] In [LR92] the query language WS OSQL was developed for WS IRIS which offers a navigational interface. Optimization techniques of OODB queries are discussed in [CD92] and [LVZ92]. In [KM90] predefined path expressions and in [OHMS92] system known path indexes are maintained for answering queries. In [KKS92] path methods are described as path expressions, which are part of an PMG Journal Paper 5 May 22, OODB query language, XSQL, to query the OODB schema. The automatic ....

Lanzelotte, R.S.G., Valduriez, P., Zait, M., Optimization of Object-Oriented Recursive Queries using Cost-Controlled Strategies, Proceedings of the 1992 ACM SIGMOD International Conference on Management of Data, San Diego, California, June 2-5, 1992, pp. 256-265.

....and randomized search strategies based on the cost of the query. The transformations can result in path traversals that can start from any point in the path (not just the endpoints) and can be interleaved with other query operations [26] This work is extended to handle recursive queries in [25] by introducing a fixpoint operator that handles the recursion. It makes use of a cost controlled search strategy. 2.2.2 Open OODB Query Optimizer The Open OODB project at Texas Instruments concentrates on the definition of an open architectural framework for OBMSs and on the description of the ....

....selection predicate of a query, it becomes important to determine the cost of applying those behaviors. In order to solve this problem for object oriented query models, a cost controlled heuristic search strategy that considers the cost of applying algebraic equivalence rules has been suggested in [25]. In order to respect encapsulation, this requires cost models for high level expressions. These cost models can be expressed in terms of costs derived for calls to an OM interface as suggested in [43] This is discussed in more detail in Chapter 7. 6.1.3 Enumerative Search Strategies Exhaustive ....

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R. Lanzelotte, P. Valduriez, and M. Zait. Optimization of object-oriented recursive queries using cost-controlled strategies. In Proc. ACM SIGMOD Int. Conf. on Management of Data, pages 256--265, 1992.

....be applied using deterministic search strategies based on the cost of the query. The transformations can result in path traversals that can start from any point in the path (not just endpoints) and can be interleaved with other query operations. This work is extended to handle recursive queries in [90]. Algebraic Rewrite A number of proposals have been made for o o optimization based on the algebraic rewrite of query expressions [15, 45, 49, 80, 112, 145, 155] For example, Beeri and Kornatzky [15] provide an extensive set of rules for bulk data types that generalize existing axioms for ....

Rosana S. G. Lanzelotte, Patrick Valduriez, and Mohamed Za it. Optimization of ObjectOriented Recursive Queries using Cost-Controlled Strategies. In SIGMOD Proceedings, pages 256--265. ACM, June 1992.

....simply that all external collection references can be treated as if they were extensional database lookups. A similar assumption is made by the CORAL system [RSS92] 6 A Composer Example We illustrate several of the features of SWORD using an example of a composer database originally from [LVZ92] The database has four classes, namely person, composer , composition, and instrument , related as shown in Figure 2. The notation set composition works means that the type of attribute works is a set of pointers to objects of class composition. The master attribute of a composer gives the ....

Rosana S. G. Lanzelotte, Patrick Valduriez, and Mohamed Zait. Optimization of object-oriented recursive queries using cost-controlled strategies. In Proceedings of ACM SIGMOD 1992 International Conference on Management of Data, pages 256--265, San Diego, CA, June 2-5 1992.

....System 17 5.2.1. Bottom Up Evaluation of ROLL The principal evaluation strategy for ROLL is bottom up, and enables the use of bulk operations which trawl the database or operate over highly interconnected sets of objects. It is based around a modified form of Processing Tree as defined by [32]. This is a form of query execution plan which represents query evaluation by means of dataflows. Processing Trees are constructed from System Graphs [29] which are an internal form used to represent a parsed query and the underlying ROLL rules which implement it. An approach based on Static ....

R. Lanzelotte and P. Valduriez. Optimization of object-oriented recursive queries using cost controlled strategies. In Proceedings of the ACM SIGMOD International Conference on the Management of Data, pp. 256--265. ACM Press (1992).

....positions. The schema information is used to prune the variable substitutions that are guaranteed to fail, say, due to the absence of an attribute that is mentioned in the query. 5 An Example We illustrate several of the features of Noodle using an example of a composer database originally from [19]. The database has four classes, namely person, composer , composition, and instrument , related as shown in Figure 2. individual composer person composition instrument class person f string name; date birthdate; g; class composition f string title; composer author ; set instrument ....

R. S. G. Lanzelotte, P. Valduriez, and M. Zait. Optimization of object-oriented recursive queries using cost-controlled strategies. In Proceedings of ACM SIGMOD 1992 International Conference on Management of Data, pages 256--265, San Diego, CA, June 2-5 1992.

....techniques for recursive RDB queries [7] are not dissimilar to the graph reordering method [11] from which the ROCK ROLL optimization method was derived. 14] describes a graph reordering optimization method for non recursive RDB queries which is similar to our global optimization strategy. [17] describes another graph reordering method for OODBs, also based on processing trees [12] although this fails to provide a description of the constraint propagation algorithm for recursive queries, and the query language is not truly object oriented i.e. does not support deductive methods, ....

R. Lanzelotte and P. Valduriez and M. Za it. Optimization of Object-Oriented Recursive Queries Using Cost Controlled Strategies. In SIGMOD, 1992.

....[M91] and VERSANT [GD91] have introduced SQL based query languages. An improved query model was developed for ORION [K90a] In [LR92] the query language WSOSQL was developed for WS IRIS, which offers a navigational interface. Optimization techniques of OODB queries are discussed in [CD92] and [LVZ92]. In [KM90] predefined path expressions and in [OHMS92] system known path indexes are maintained for answering queries. In [KKS92] path methods are described as path expressions, which are part of an OODB query language, XSQL, to query the OODB schema. The automatic generation of joins in ....

Lanzelotte RSG, Valduriez P, Zait M (1992) Optimization of Object-Oriented Recursive Queries using Cost-Controlled Strategies, Proceedings of the 1992 ACM SIGMOD International Conference on Management of Data, San Diego, Calif., pp 256--265

....in an object oriented query. Therefore recognition and elimination of these common subexpressions is an important optimization. Some work has been done at the source level by Cluet and Delobel[20] but they give no description of how their work impacts the plan generation stage. Lanzelotte, et al. [58, 59, 38, 60] are able to recognize common subexpressions by mapping queries onto the physical schema. Common subexpressions in path expressions appear in the class connection graph, a result of this mapping process. As previously mentioned, Kemper et al. 55] can eliminate common subexpressions that appear via ....

....appear in the class connection graph, a result of this mapping process. As previously mentioned, Kemper et al. 55] can eliminate common subexpressions that appear via access support relations, and Rexall[88] can be used to recognize algorithmic common subexpressions. Lanzelotte, et al. [58, 59, 38, 60] took the first step towards rewriting at the physical level by mapping their queries onto the schema. This is done using two data structures, the class connection graph and the physical schema graph. The class connection graph is a nonnavigational representation of the implicit (path traversals) ....

Rosana S. G. Lanzelotte, Patrick Valduriez, and Mohamed Zait. Optimization of objectoriented recursive queries using cost-controlled strategies. In Stonebraker [79], pages 256--257.

....query processing [26] the major problem to be addressed is dealing with a large space of parallel execution plans. In the centralized case, the search space gets obviously larger as the query is more complex, e.g. includes many joins [27] deals with complex objects [21] or includes recursion [20]. This work was partially funded by the Esprit projects EDS and IDEA. 1 Even for a reasonable query (e.g. with less than 10 joins) a parallel dataflow execution model with fragmented data placement yields a very large range of alternative execution strategies. We believe that considering a ....

R.S.G. Lanzelotte, P. Valduriez, and M. Zait. Optimization of object-oriented recursive queries using cost-controlled strategies. In Proc. ACM SIGMOD, 1992.

....We did not deal either with the optimization of user defined methods, which is still an open problem. Regarding recursion, we adopted the typical rewriting approach, i.e. prior to cost based optimization. Even after realizing that this simplified approach may lead to missing the best plan [19], we insisted in adopting it because it was hard to find meaningful counterexamples in our pilot applications. Besides, we felt there were too many (maybe too good) papers on this topic. Besides coping with the novelties of the input language and the execution environments, we also aimed at ....

....of our optimizer project have been presented in several papers. We have designed several techniques to optimize the access to objects through path expressions [21] Having adopted a rewriting approach to deal with objects and recursion, we realized that this could lead to missing the best plan [19]. With respect to parallelism, we proposed a new way of scheduling execution plans, using zigzag trees, which are well suited to shared memory environments with resource contention [33] We defined a cost metric that captures the main aspects of parallel execution environments, i.e. the operation ....

R.S.G. Lanzelotte, P. Valduriez, and M. Zait. Optimization of object-oriented recursive queries using cost-controlled strategies. In Proc. ACM SIGMOD Int. Conf. on Management of Data, pages 256--265, 1992.

....query processing [17] the major problem to be addressed is dealing with a large space of parallel execution plans. In the centralized case, the search space gets obviously larger as the query is more complex, e.g. includes many joins [18] deals with complex objects [14] or includes recursion [13]. Even for a reasonable query (e.g. with less than 10 joins) a parallel dataflow execution model with fragmented data placement yields a very large range of alternative execution strategies. We believe that considering a large search space, rather than relying on restrictive heuristics, is ....

R.S.G. Lanzelotte, P. Valduriez, and M. Zait. Optimization of object-oriented recursive queries using cost-controlled strategies. In Proc. ACM SIGMOD, 1992.

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Lanzelotte R., Valduriez P., Zait M., "Optimization of Object-Oriented Recursive Queries using Cost-Controlled Strategies", ACM SIGMOD Int. Conf., 1992.

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