C. Kilger and G. Moerkotte. Indexing multiple sets. In Proc. Int. Conf. on Very Large Data Bases (VLDB), pages 180--191, Santiago, Chile, Sept. 1994.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....nodes sorted by the value of their start labels. Again, updates are an issue. See Sect. 7. 3.2 Index storage There is a rich history of work on index structures suited to specific purposes. In particular, we draw inspiration from the work done in the context of object oriented systems, such as [33]. More recently, novel path indices have been proposed for XML and semi structured data [41,32,18] Schema summarization structures have also been proposed [27,28] We are intensively studying this problem, but at the current time have only single node indices implemented in Timber. We construct ....

C. Kilger, G. Moerkotte (1994) Indexing multiple sets. Proc. VLDB Conf., pp 180--191, Sept

....nodes sorted by the value of their start labels. Again, updates are an issue. See Sec. 7. 3.2 Index Storage There is a rich history of work on index structures suited to specific purposes. In particular, we draw inspiration from the work done in the context of object oriented systems, such as [7,29]. More recently, novel path indices have been proposed for XML and semi structured data [15, 28, 37] Schema summarization structures have also been proposed [23, 24] We are intensively studying this problem, but at the current time have only single node indices implemented in Timber. We ....

C. Kilger and G. Moerkotte. Indexing Multiple Sets. Proc. VLDB Conf., pages 180--191, Sept. 1994.

....simple class attribute (such as the string, integer or boolean) A nested predicate is issued against a nested attribute which contains a reference to an object in the domain of another class. The most intensively studied query type was indexing an inheritance hierarchy against a simple attribute [KKD89, LOL92, KiMo94, KaRa94]. The class hierarchy index (CHindex) KKD89] is based on B trees and maintains a single index for all classes in the inheritance hierarchy. The CHindex efficiently performs match point operations, but is not optimal for range queries. Conversely, H index [LOL92] efficiently performs range ....

....match point operations, but is not optimal for range queries. Conversely, H index [LOL92] efficiently performs range operations and reads more pages than CH index when match point queries are executed. As a result, a method combining the advantages of both CHand H trees has been proposed in [KiMo94]. A different approach to the problem has been proposed by Kanellakis, Ramaswamy at al. KaRa94] They reduced the indexing a simple class attribute to external dynamic 2dimensional range searching and exploited data structures studied in computational geometry. Most techniques for indexing an ....

Kilger, Ch., Moerkotte, G., 1994, Indexing Multiple Sets. In Proc. 20th VLDB Conf., pp. 180-191.

....mapping yields a significant query performance enhancement in a multikey type index. 1 Introduction Multikey index structures have been discussed as an alternative to traditional, B tree based search structures in the context of type hierarchy indexing (see [RK95] KRVV93] [KM94] and [MP95] The key idea is to incorporate the type hierarchy structure of a given database scheme into a standard multikey index implementation in such a way that the hierarchy is mapped to one of the multikey index domains (called type domain in the sequel) The result is a so called multikey ....

....Other proposals extend B trees, e.g. the Class Hierarchy Index [KKD89] maintaining a common B tree for all types and an additional leave node organization scheme. Single type B trees nested according to the inheritance hierarchy are introduced in [LOL92] as H trees. CG trees [KM94] and hcC trees [SS94] extend B trees with multiple lists to organize OIDs according to type membership. The paper is structured as follows: Section 2 contains a detailed problem statement, i.e. a rationale for optimal hierarchy linearizations. The mapping algorithm used to find optimal ....

Christoph Kilger and Guido Moerkotte. Indexing multiple sets. In VLDB'94 [VLD94], pages 180--191.

....in one uniform index, combined class path hierarchy index, and with that it is able to answer queries which are not answerable with the previous index schemes. Recently, two index structures have appeared which have similar goals to the U index structure. The first structure, called CG trees [6], addresses only the class hierarchy case, but it provides generally good performance for both key grouping and set grouping (see definitions below) thus providing a compromise between CH index and H trees. A full comparison of the performance of the U index scheme vs. CG trees is presented in ....

....Company Division City Employee Auto Company Truck Company Japanese Auto Company Vehicle Color Age Manufactured By Of Located In President Of Fig. 1: A Object Oriented Database Schema Recently, two important index structures have appeared. The CG tree index by Kilger and Moerkotte [6] provides a compromise between the key grouping of CH trees and the set grouping of H trees. It achieves that by having a set directory like CH trees, but at the leaf level it provides two features which helps in the set grouping, these are: link pointers between leaf pages of the same set, and ....

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G. Moerkotte and C. Kilger. Indexing multiple sets. In Proc. 20th VLDB Conference, Santiago, Chile (1994).

....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 may contain method invocation. The behavioral indexing technique is based on pre computation of method results and storing them into an index. Previous work on behavioral indexing includes [15, 12, 13, 14, 2, 7] The effects of two indexes could be entangled, that ....

Christoph Kilger and Guido Moerkott. Indexing multiple sets. In Proceeding of the 20th VLDB Conference Santiago, Chile, pages 180--191, 1994.

....the design of specific indexing techniques. Indexing techniques so far proposed can be classified into three groups: inheritance indexing techniques, aggregation indexing techniques, integrated techniques [8] The first group includes techniques supporting queries along inheritance hierarchies [10, 11, 13, 14]. Most of those techniques have been defined as extensions of the class hierarchy index (CHindex) 11] The CH index is based on B trees and maintains a single index for all classes in y Recommended by Patrick O Neil 66 Elisa Bertino et al. the given inheritance hierarchy. The CH index ....

C. Kilger and G. Moerkotte. Indexing Multiple Sets. In Proc. of the 20th Int. Conf. on Very Large Data Bases, pages 180--191, Santiago, Chile, 1994. 108 Elisa Bertino et al.

....or class hierarchy, as the attributes of superclasses are inherited by their subclasses in object oriented data models. In this perspective, we face the problem of indexing attributes among the class hierarchy. There are good structures for this purpose such as CH index [14] H tree [19] CG tree [15], HcC tree [31] In our system, to index temporal dimension for content objects, we use IB trees [3] We emphasize that we basically need a good index structure on intervals as the temporal attributes of content objects are in the form of timeintervals. Below, we focus on indexing intervals in the ....

Kilger, C., Moerkotte, G., "Indexing Multiple Sets", Proceedings of the 20th VLDB Conference, 1994, pp. 180-191.

....path corresponding to the component are stored, and any two objects in the two classes could be connected by more than one object path. Further, an update on one object may need to be propagated to several components or to the entire index[24] tree[6] CH tree [18] H tree [21] and CG tree [17], will not be discussed in this paper. access support relation, which could be costly. Hua and Tripathy [12] propose a navigation structure called object skeleton which essentially is a network of object identifiers. The two object identifiers are connected if the corresponding objects are ....

C. Kilger and G. Moerkotte. Indexing multiple sets. In Proc. Int. Conf. Very Large Database, Santiago, Chile, September 1994.

....efficiently search or update the objects of a class according to a (range of) value(s) of an attribute, impacts OODB performance heavily. For this indexing problem, most systems use the class hierarchy index (CH) technique of [15] implemented using B trees. Other techniques, such as those of [14,18,30], can lead to improved average case performance but involve the implementation of new data structures, which are not as well understood parts of database technology as B trees. As a special form of external dynamic two dimensional range searching, this OODB indexing problem is solvable within ....

....is a special case of external dynamic two dimensional range searching (see below) Together with the different problem of nested object indexing (as in [4,11,13, 19] it constitutes the current repertoire of OODB indexing problems. Class Indexing has been examined in [15] and more recently in [14,18,30]. These solutions are heuristic (with poor worst case performance) and have been supported by experimental performance evaluation. Of these, the class hierarchy index (CH) solution of [15] is the only method used widely in practice. We believe this is the case because it was the first reasonable ....

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C. Kilger and G. Moerkotte, "Indexing Multiple Sets," Proc. 1994 VLDB Conference.

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C. Kilger and G. Moerkotte. Indexing multiple sets. In Proc. Int. Conf. on Very Large Data Bases (VLDB), pages 180--191, Santiago, Chile, Sept. 1994.

.... algorithms to support spatial joins have been developed [3, 14, 19, 26, 32] Another special join algorithm has been developed for joining objects on set valued attributes [18] Another important research area is the development of index structures that allow to accelerate the evaluation of joins [16, 22, 23, 31, 39, 40]. However, if there is no selection prior to a join or the selections exhibit a high selectivity value (i.e. many output tuples are produced) the performance gain of these algorithms is limited. This is also true for bitmap join indices [31] that were developed especially for Data Warehouse ....

C. Kilger and G. Moerkotte. Indexing multiple sets. In Proc. Int. Conf. on Very Large Data Bases (VLDB), pages 180--191, Santiago, Chile, Sept. 1994.

.... the sort merge and hash joins see [13, 14] A lot of effort has also been spent on parallelizing join algorithms based on sorting [10, 25, 26, 34] and hashing [6, 12, 36] Another important research area is the development of index structures that allow to accelerate the evaluation of joins [16, 22, 21, 29, 40, 42]. All of these algorithms concentrate on simple join predicates based on the comparison of two atomic values. Predominant is the work on equi joins, i.e. where the join predicate is based on the equality of atomic Permission to copy without fee all or part of this material is granted provided ....

C. Kilger and G. Moerkotte. Indexing multiple sets. In Proc. Int. Conf. on Very Large Data Bases (VLDB), pages 180--191, Santiago, Chile, Sept. 1994.

.... the sort merge and hash joins see [13, 14] A lot of effort has also been spent on parallelizing join algorithms based on sorting [10, 25, 26, 34] and hashing [6, 12, 36] Another important research area is the development of index structures that allow to accelerate the evaluation of joins [16, 21, 20, 29, 40, 42]. All of these algorithms concentrate on simple join predicates based on the comparison of two atomic values. Predominant is the work on equi joins, i.e. where the join predicate is based on the equality of atomic values. Only a few articles deal with special issues like non equi joins [9] ....

C. Kilger and G. Moerkotte. Indexing multiple sets. In Proc. Int. Conf. on Very Large Data Bases (VLDB), pages 180--191, Santiago, Chile, Sept. 1994.

....advantages of (1) being easily implementable and (2) resulting only in a neglectable increase in optimization time. 1 Introduction Since the introduction of OBMS, much work has been devoted to optimizing object queries. Special index structures for path indexes [2, 12, 18, 20] class indexes [17, 16], and function materialization [11] have been proposed. Logical optimization techniques have been developed. They cover path evaluation [1, 13] factorization [5] unnesting [6, 19] optimization in the presence of expensive methods [9, 15] disjunctions [14] or aggregates [7] Looking at all the ....

....[14] or aggregates [7] Looking at all the effort, it is surprising, that, in the context of query optimization, class hierarchies did not receive special attention. The only special support developed so far are index structures that are capable to index multiple sets or classes in a hierarchy [17, 16, 20]. So far, no effort has been made to exploit class hierarchies to optimize queries that refer to classes integrated into a class hierarchy. The goal of the paper is to start investigations in this direction. Either because they are made available to the users or because of preliminary rewritings ....

C. Kilger and G. Moerkotte. Indexing multiple sets. In Proc. Int. Conf. on Very Large Data Bases (VLDB), pages 180--191, Santiago, Chile, Sept. 1994.

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