D. Maier and J. Stein. Indexing in an object-oriented DBMS. In Proc. IEEE Intl. Workshop on Object-Oriented Database Systems, Asilomar, Pacific Grove, CA, pages 171--182. IEEE Computer Society Press, 1986.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....introduced in [10J constitute one such approach. Access support re lations form the basis of the query optimization strategy in the GOM (Generic Object Model) database system. They are a generalization of an indexing technique for path expressions first proposed for the GemStone data 29O model [15] and, later, applied to OR ON in [1] Whereas the GemStone (and ORION) path expressions were limited to only single valued attributes the access support relatiofis allow also set valued attributes along the path. Also, access support relations can be maintained in four different extensions, ....

D. Mater and J. Stein. Indexing in an object-oriented DBMS. In K. R. Dittrich and U. Dayal, editors, Proc. IEEE Intl. Workshop on Object-Oriented Database Systems, Asilomar, Pacific Grove, CA, pages 171- 182. IEEE Computer Society Press, Sep 1986.

....index lookup in our language. We can therefore fully describe a join index by a triple consisting of a materialized binary relation view and two indexes. In our example, the join index for joining Dept with Proj is (Dept, I, JI) Access support relations [KM90a, KM90b] generalize path indexes [MS86, Ber94, BK89] and translate the join index idea from the relational to the object model, generalizing it from binary to n ary relations. An access support relation (ASR) for a given path is a separate precomputed relation that explicitly stores the oids of objects related to each other via the ....

D. Maier and J. Stein. Indexing in an object-oriented dbms. In Proceedings of 2nd International Workshop on Object-Oriented Database Systems, pages 171--182, Asilomar, CA, September 1986.

....the efficiency of its representation through a fast lookup operation that appears in query plans. It turns out that dictionaries represent in a natural fashion physical structures such as primary and secondary indexes, extent based representations of OO classes, join indexes [46] path indexes [34], access support relations [28] gmaps [45] etc. The physical level is represented just like the logical level is, with a typed data definition language and with constraints. Constraints In a previous paper [37] we have generalized the classical relational tableau chase procedure [9] to work for ....

....surrogates to index into the relations. We can therefore fully describe a join index by a triple consisting of a materialized binary relation view and two indexes. In our example, the join index for joining Dept with Proj is (Dept, I, JI) Access support relations [28, 29] generalize path indexes [34, 10, 11] and translate the join index idea from the relational to the object model, generalizing it from binary to n ary relations. An access support relation (ASR) for a given path is a separate precomputed relation that explicitly stores the oids of objects related to each other via the attributes of ....

D. Maier and J. Stein. Indexing in an object-oriented dbms. In Proceedings of 2nd International Workshop on Object-Oriented Database Systems, pages 171-- 182, Asilomar, CA, September 1986.

....grouped together into a single file or table. This is the only grouping supported directly by the system and is the basis for queries in these systems. By contrast, some object oriented databases support user defined sets that group together specific objects of the same type (for example, GemStone[12, 47, 48]) and we would like to support queries over these user defined sets. In such a system, an object can be an element of more than one user defined set. For example, consider a database containing objects representing employees and departments. Each department could contain a set of employees and if ....

....objects of a type need not have the same representation; there may be objects of the same type that have different representations. Furthermore, new implementations of types can be added to the database system dynamically. Schemes that base queries on path expressions (for example, GemStone[47]) violate abstraction and encapsulation. They require knowledge of the implementation of a type to name the path of interest, constrain types to one representation, and require that the key values of interest be represented directly in the type s implementation. Method precomputation schemes[8, ....

[Article contains additional citation context not shown here]

David Maier and Jacob Stein. Indexing in an object-oriented DBMS. In Proceedings of 1986.

....furnishing its own compiler [19] It does use a tool to parse C class representations and virtual memory techniques to manage persistence. These techniques are not suitable for embedded environments that do not provide virtual memory. Some object oriented database systems, such as GemStone [24], provide automatic index maintenance using pathbased indexing. Here, keys are expressed as paths of instance variables stored in objects. There are several problems with this approach. First, it does not support keys derived from multiple instance variables. Second, evaluating keys and noticing ....

D. Maier and J. Stein. Indexing in an object-oriented dbms. In Proceedings of International Workshop on Object-Oriented Database Systems, 1986.

....that refers to another object, then OdeView automatically makes available a sliding menu with elements that are members of the referenced object. This is indicated to the user by an arrow on the right hand side of the member name. This mechanism allows the user to specify a path expression [15] (a.k.a implicit join ) of any length. Figure 6 shows the operand menu for employee with sliding menus for department and manager. 8 Figure 6: Sliding operand menus 4.1.2 Operators The Extend button is used for extending the specified query expression by applying some operator to it. ....

D. Maier and J. Stein, "Indexing in an Object-Oriented DBMS", Proc. Int'l Workshop ObjectOriented Database Systems, Asilomar, California, Sept. 1986.

....store method results in relations so that they can be reused across multiple queries over a period of time. Graefe provides an annotated bibliography of these ideas in Section 12.1 of his query processing survey [Gra93] Persistent caches are akin to materialized views [GM95] or function indices [MS86, LS88] from the point of view of a single query, they represent precomputed methods, rather than caches which are generated and used on the fly. Persistent caches are used in a way that is analogous to techniques for avoiding recomputation of common relational subexpressions [Sel88] In order ....

D. Maier and J. Stein. Indexing in an ObjectOriented DBMS. In Klaus R. Dittrich and Umeshwar Dayal, editors, Proc. Workshop on Object-Oriented Database Systems, pages 171-- 182, Asilomar, September 1986.

....For each relation (or level in the hierarchy) an index based on its key is maintained, which yields the key of the parent. In the object oriented literature, indexes which yield parent identifiers are often called step indexes. They are called Maier Stein indexes in this chapter after the paper [25]. Since this seems to be the indexing of choice in most commercial object oriented systems, it is used in the experiments rather than some of the proposed indexes in the academic literature such as path indexes [5] or access support relations [19] In addition, in many of the experiments, only one ....

D. Maier and J. Stein. Indexing in an object-oriented DBMS. In Proc. Int. Workshop Object-Oriented Database Systems, pages 171--182, 1986.

....if a DTD is speci ed, disjunction and recursion within an element speci cation lead to a potential in nite set of possible paths. Further, access support relations were not designed to cover generalized path expressions, i.e. those containing wild cards. This is also true for other path indexes [2, 11, 12, 15]. 1 www.goxml.com 2 www.ibm.com xml 3 Xyleme is a joint project between INRIA Rocquencourt and the University of Mannheim. The rest of the paper is organized as follows. Section 2 introduces the Mumpits query language. Section 3 discusses the design and implementation of Mumpits. Section 4 ....

D. Maier and J. Stein. Indexing in an object-oriented DBMS. In Proc. IEEE Intl. Workshop on Object-Oriented Database Systems, Asilomar, Pacic Grove, CA, pages 171-182. IEEE Computer Society Press, 1986.

....Classes Indexing by one attribute and by class name in an object oriented model, where objects are organized as a static forest hierarchy of classes, is also a special case of external dynamic two dimensional range searching. Together with the different problem of indexing nested objects, as in [26], it constitutes the basis for indexing in object oriented databases. Indexing classes has been examined in [22] and more recently in [25] but the solutions offered there are largely heuristic with poor worst case performance. In Section 3.2, we reduce indexing classes to a special case of ....

D. Maier & J. Stein, "Indexing in an Object-Oriented DBMS," IEEE Proc. International Workshop on Object-Oriented Database Systems (1986). 105

....The value of an attribute of an object is an object or a set of objects. The access scope of a query may include the nested attributes, which is essentially object accesses along references chains from one object instance to another. Methods for this support of nested predicates can be found in [20, 6, 13, 14, 24, 10, 11, 8]. b) For inheritance hierarchy: The access scope of a query against a class may include instances of the class and those of its subclasses. An index structure can support both instances in the same search index. Previous work includes [17, 1, 18, 19, 16, 22, 21] 2. Behavioral For OODB, queries ....

D. Maier and J. Stein. Indexing in an object-oriented dbms. In Proceedings IEEE International Workshop on Object-Oriented Database Systems, pages 171--182, 1986.

....than relating only two relations (or object types) our technique allows to support access paths of arbitrary length. Our indexing technique subsumes and extends several other previously proposed strategies for optimizing access along attribute chains in object bases. The index paths in GemStone [7] are restricted to chains that contain only single valued attributes and their representation is limited to binary partitions of the access path. Similarly, the object oriented access techniques described for the Orion model [6, 1] are extended in several dimensions in our framework. Our technique ....

D. Maier and J. Stein. Indexing in an object-oriented DBMS. In K. R. Dittrich and U. Dayal, editors, Proc. IEEE Intl. Workshop on Object-Oriented Database Systems, Asilomar, Pacific Grove, CA, pages 171-- 182, IEEE Computer Society Press, Sep 1986.

....Classes Indexing by one attribute and by class name in an object oriented model, where objects are organized as a static forest hierarchy of classes, is also a special case of external dynamic 2 dimensional range searching. Together with the different problem of indexing nested objects, as in [23], it constitutes the basis for indexing in object oriented databases. Indexing classes has been examined Diagonal corner query Diagonal corner query 3 sided query 2 sided query general 2 dimensional query Figure 1: Diagonal corner queries, 2 sided, 3 sided and general 2 dimensional range ....

D. Maier and J. Stein, "Indexing in an Object-Oriented DBMS," IEEE Proc. International Workshop on Object-Oriented Database Systems (1986), 171--182.

....literature. For each relation (or level in the hierarchy) an index based on its key is maintained, which yields the key of the parent. In the object oriented literature, indexes which yield parent identifiers are often called step indexes. They are called Maier Stein indexes here after the paper [MS86]. Since this seems to be the indexing of choice in most commercial object oriented systems, it is used in the experiments rather than some of the proposed indexes in the academic literature such as path indexes [BK89] or access support relations [KM90] In addition, in many of the experiments, ....

D. Maier and J. Stein. Indexing in an objectoriented DBMS. In Proc. Int. Workshop ObjectOriented Database Systems, pages 171--182, 1986.

.... Access Support Relations constitute a generalization of binary join indices originally proposed for the relational model [4] and later extended for object models [5, 6] Binary join indices are an extension of links, developed by Harder [7] The binary links were also applied to object models in [8, 9]. For illustrating the main idea of access support relations let us introduce a sample object base schema modelling a department store in the sequel we will call the schema DeptStore: type EMP is [ Name: STRING; WorksIn: DEPT; Salary: INT; type MANAGER supertype EMP is [ Cars: fCARg; ....

D. Maier and J. Stein, "Indexing in an object-oriented DBMS," in Proc. IEEE Intl. Workshop on ObjectOriented Database Systems, Asilomar, Pacific Grove, CA (K. R. Dittrich and U. Dayal, eds.), pp. 171--182, IEEE Computer Society Press, Sep 1986.

.... the following method that returns the social security number of an Employee s kid with name kname : define Employee function get ssnum (kname: char[ returns int4 ( retrieve (this.kids.ssnum) where (this.kids.name = kname) we may be able to take advantage of indices or cached attributes [Maie86b, Shek89] if a particular Employee (or set of Employees) has such enhancements. This also allows for transformations that involve nodes in the stored query tree interacting with nodes in the invoking query tree; some examples of this can be found in [Beer90] Thus we want to be able to optimize the ....

D. Maier and J. Stein, "Indexing in an Object-Oriented DBMS," Tech. Report CS/E-86-006, Oregon Grad. Center, Beaverton, Oregon, May 1986.

....navigation via the traversal of representation exposingpath expressions, e.g. x.project.manager.salary, or, preferably, the invocation of arbitrary methods or functions, e.g. x. manager salary( Current commercial OODBs support efficient index based associative access for path expressions [6, 7, 16, 18, 20], while future OODBs should support indexes over methods and functions [14] Such query languages are a good way to describe hoarding profiles, supporting both simple requests (e.g. prefetch all sections of the paper I am working on) and complex ones. It is likely that queries useful for hoarding ....

D. Maier and J. Stein. Indexing in an Object-Oriented DBMS. In Proc. 1986 Int. Workshop on Object-Oriented Database Systems, pages 171--182, Pacific Grove, CA, September 1986.

....by Valduriez [11] Rather than relating only two relations (or object types) our technique allows to support access paths ranging over many types. Our indexing technique subsumes and extends several previously proposed strategies for access optimization in object bases. The index paths in GemStone [6] are restricted to chains that contain only single valued attributes and their representation is limited to binary partitions of the access path. Similarly, the object oriented access techniques described for the Orion model [5] are contained as a special case in our framework. Our technique ....

D. Maier and J. Stein. Indexing in an object-oriented DBMS. In K. Dittrich and U. Dayal, editors, Proc. IEEE Intl. Workshop on Object-Oriented Database Systems, pages 171--182, Asimolar, Pacific Grove, CA, Sept 1986. IEEE Computer Society Press.

....this paper, we restrict both gmap definitions and queries to project select join (psj) expressions over a simple semantic data model. We demonstrate that such expressions are powerful enough to express most conventional storage structures, as well as more exotic techniques such as path indices [2, 16], field repliPage cation [11, 23] and more. We present an algorithm to translate user queries, expressed as psj queries over structures in the logical schema, into relational expressions over the gmaps. We also show how this translation can be integrated into a conventional query optimizer. ....

....is to add Dept.name to the select clause. In the previous examples, the gmap data included all Faculty instances. However, there are cases where we frequently access only some instances of a domain. Object oriented systems that store instances in explicit collections rather than class extents [5, 16, 18] allow the creation of collection indices, which provide fast access paths only to the subsets of the domains that are included in the collection. Our gmap definition language is powerful enough to express such indices by using restrictions. An example of this technique was shown in Figure 2 ....

[Article contains additional citation context not shown here]

D. Maier and J. Stein. Indexing in an Object-Oriented DBMS. In 2nd Int. Workshop on Object-Oriented Database Systems, pages 171--182, Asilomar, CA, Sept. 1986.

....(OODB) data models results in a larger number of implementation choices. The database designer may consider clustering versus normalization for various nested collections in the database, create inverse links, attach secondary indices, materialize functions and views, partition large objects, etc. [15, 14, 23, 4]. It is highly desirable to have these choices isolated from the conceptual model itself, leaving the application programmer to worry only about what data to retrieve, not how to retrieve the data. Achieving the same degree of data independence in an OODB system as in a relational database system ....

D. Maier and J. Stein. Indexing in an Object-Oriented DBMS. In International Workshop on Object-Oriented Database Systems, Asilomar, CA, pp 171--182, September 1986.

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D. Maier and J. Stein. Indexing in an object-oriented DBMS. In Proc. IEEE Intl. Workshop on Object-Oriented Database Systems, Asilomar, Pacific Grove, CA, pages 171--182. IEEE Computer Society Press, 1986.

No context found.

D. Maier and J. Stein. Indexing in an object-oriented DBMS. In K. R. Dittrich and U. Dayal, editors, Proc. IEEE Intl. Workshop on Object-Oriented Database Systems, Asilomar, Pacific Grove, CA, pages 171--182. IEEE Computer Society Press, Sep 1986.

No context found.

D. Maier and J. Stein. Indexing in an object-oriented DBMS. In K. R. Dittrich and U. Dayal, editors, Proc. IEEE Intl. Workshop on Object-Oriented Database Systems, Asilomar, Pacific Grove, CA, pages 171-- 182. IEEE Computer Society Press, Sep 1986.

No context found.

D. Maier and J. Stein. Indexing in an object-oriented DBMS. In K. R. Dittrich and U. Dayal, editors, Proc. IEEE Intl. Workshop on Object-Oriented Database Systems, Asilomar, Pacific Grove, CA, pages 171-- 182. IEEE Computer Society Press, Sep 1986.

No context found.

Maier, D. and Stein J., "Indexing in Object-Oriented DBMS," Proceedings of International Workshop on Object-Oriented Databases, 1986. nd fvNameN|="w n "| 195

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