H. Riedel and M.H. Scholl. A formalization of ODMG queries. In Seventh IFIP 2.6 Working Conference on Database Semantics (DS-7), 1997.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....complete. There is obviously a need for a more formal, mathematical presentation; the informal English presentation may be eloquent but it leaves a lot of space for ambiguity and misinterpretation. Riedel and Scholl set out to describe the type system underlying the ODMG object model formally [RS97] However, their approach, reflected in the CROQUE version of ODL, differs considerably from the type model as defined in the ODMG standard [CBB 00] They propose a type based object model, where object types need not be named, since they are distinguished uniquely by their set of functions ....

H. Riedel and M.H. Scholl. A formalization of ODMG queries. In Seventh IFIP 2.6 Working Conference on Database Semantics (DS-7), 1997.

....enable Java objects to be passed into OQL queries, clearly require the Java objects to be re typed under the ODMG type system (again we assume this is why the ODMG specified a QueryParameterTypeInvalidException method) How this is achieved, however, is clearly system specific. Riedel and Scholl [9] also set out to describe formally the type system underlying the ODMG object model. There are certainly strong similarities between their presentation and ours, but also some differences. Firstly, they study a much earlier version of the Standard (version 1.2) so some of their work is no longer ....

H. Riedel and M.H. Scholl. A formalization of ODMG queries. In Proceedings of the 7th IFIP 2.6 Working Conference on Database Semantics, 1997.

....as well as a classification represented in a tabular fashion are given in Section 3. We started our research investigating query optimization by algebraic rewriting in an object oriented framework. This was done in the CROQUE 1 [HK96, GGMS97] project where OQL ( Cat96] formalized in [RS97] queries are optimized through rewriting among other methods. But we think that the ordering of rules is a much more general problem, that should be of interest in the framework of relational (rule based) query optimization, too. Moreover, the rule based paradigm is not limited to algebraic ....

H. Riedel and M.H. Scholl. A Formalization of ODMG Queries. In Proc. of the 7th Int. Conference on Database Semantics (DS-7), Leysin, Switzerland, October 1997. 14

....query rewriting, search strategies, heuristics 1 Introduction The CROQUE project 1 [HK96, SGG 97] is concerned with different aspects of the optimization and evaluation of object oriented queries. Starting points of all our considerations are queries in ODMG s OQL ( Cat96] formalized in [RS97] that are first represented internally in a hybrid approach of calculus and algebra [GKG 97] before being transformed using a rule and cost based optimizer. The already developed cost model [KJH98] is not further discussed in this paper. In CROQUE, rule based rewriting spans a space ....

H. Riedel and M.H. Scholl. A Formalization of ODMG Queries. In Proc. of the 7th Int. Conference on Database Semantics (DS-7), Leysin, Switzerland, October 1997.

....most of the present query optimizers without almost any effort. 1 Introduction The CROQUE project 1 [8] is concerned with different aspects of the optimization and evaluation of object oriented queries. Starting points of all our considerations are queries in ODMG s OQL ( 1] formalized in [22]) that are first represented internally in a hybrid approach of calculus and algebra [5] before being transformed using a rule and cost based optimizer. The already developed cost model is not further discussed in this paper. In CROQUE, rule based rewriting spans a space of equivalent query ....

H. Riedel and M.H. Scholl. A Formalization of ODMG Queries. In Proc. of the 7th Int. Conference on Database Semantics (DS-7), October 1997.

....rule classes, rule ordering. 1 Motivation: rule based optimization The CROQUE project 1 [HK96, SGG 97] is concerned with different aspects of optimization and evaluation of object oriented queries. Starting point of all our considerations are queries in ODMG s OQL ( Cat96] formalized in [RS97] that are first represented internally employing a hybrid approach of calculus and algebra [GKG 97] before being transformed using a rule and cost based optimizer. The cost model has already been developed. The conceptual development of the rule based component (and therefore of parts ....

H. Riedel and M.H. Scholl. A Formalization of ODMG Queries. In Proc. of the 7th Int. Conference on Database Semantics (DS-7), Leysin, Switzerland, October 1997.

....more than one ( n best ) alternatives for further evaluation. 1 Motivation The CROQUE project 1 [4, 2] is concerned with different aspects of optimization and evaluation of object oriented queries. Starting point of all our considerations are queries in ODMG s OQL ( 1] formalized in [6]) that are first represented internally employing a hybrid approach of calculus and algebra [3] before being transformed using a rule and cost based optimizer. In general, equivalence rules may be applied in both directions. Since in most cases a heuristically preferred direction of ....

H. Riedel and M.H. Scholl. A Formalization of ODMG Queries. In Proc. of the 7th Int. Conference on Database Semantics (DS--7), Leysin, Switzerland, October 1997.

....their complex types. Arbitrarily complex objects can be modelled using several type constructors (like set, struct, list, bag, array) Also the distinction between objects (with an value independent identity) and literals (without oid) is supported. The schema is described by an ODL notation. In [RS96, RS97] we gave a formal definition of the ODMG model. So we can formally argue on inheritance and queries in this approach. Due to space limitations, we do not repeat the formalism here, but describe informally the important aspects w.r.t. objects and classes. The set of all (abstract) objects is ....

....management system makes some parts of the data invisible to the user (and might delete these parts as well) Example 3 We are asking for the available details for existing workpieces using the query select w.is of details from Workpiece w. Using the OQL type checker using the formalization from [RS96, RS97], the result type is bag set struct detail:string,added by:Engineer . But according to the temporal versioning schema of the classes Workpiece and Product and the current available objects refering to products of P2 have only restricted information on details, while workpieces of W3 have no ....

H. Riedel and M. H. Scholl. A Formalization of ODMG Queries. In 7th Intl. Conference on Data Semantics (DS-7), 1997.

....get involved in a given context. 4.1 Formalization of temporal constructs In the following, we describe most of the constructs for handling histories in TEMPOQL. For each construct, we give in figures 2 and 3, its typing rules, its syntax and its semantics, using a notation similar to that of [RS97] which provides a complete formalization of OQL queries. More precisely, the formalization of a construct is made up of four parts: Gamma Context: it describes subtyping constraints on the types appearing in the typing part, as well as some constraints on sub queries (such as a variable being ....

H. Riedel and M.H. Scholl. A formalization of ODMG queries. In Proc. of the 7th Int. Conference on Data Semantics (DS-7), Leysin, Switzerland, October 1997. Chapman & Hall.

....are implementation dependent and will be discussed in section 6. 5.2.3 Querying histories In the following, we describe most of the constructs for handling histories in TempOQL. For each construct, we give its typing rule, its syntax and its semantics, using a notation similar to that of [RS97] which provides a complete formalization of OQL queries. More precisely, the formalization of a construct is made up of four parts: Preconditions: they describe subtyping constraints on the types appearing in the typing part, as well as some constraints on sub queries (such as a variable being ....

H. Riedel and M.H. Scholl. A formalization of ODMG queries. In Proc. of the 7th Int. Conference on Data Semantics (DS-7), Leysin, Switzerland, October 1997. Chapman & Hall.

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