C. C. Low, B. C. Ooi, and H. Lu, "H-trees: A Dynamic Associative Search Index for OODB," Proc. ACM SIGMOD (1992), 134--143.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....that answering 3 sided queries efficiently is key to solving the problem of indexing classes. Indexing classes is the natural generalization of indexing in the context of objectoriented databases and is very important to their good performance (see [KiL, ZdM] for more information on this area) [KKD, LOL] present solutions to the problem of indexing classes. However, their algorithms are based on heuristics and cannot guarantee good worst case performance. Previous attempts to answer 3 sided queries in secondary memory by implementing priority search trees in secondary memory [IKO, KRV] did not ....

C. C. Low, B. C. Ooi, and H. Lu, "H-trees: A Dynamic Associative Search Index for OODB," Proc. ACM SIGMOD (1992), 134--143.

....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 external dynamic twodimensional range searching called three sided searching. Three sided range queries are a special case of two dimensional ....

....this is the method used most often in object oriented database systems, for example, the O2 database system [1] and thus we use it as our point of reference for the methods we propose. The only other method for indexing classes appearing in the literature is a scheme called the H tree [25], based on the idea of threading many B trees together to facilitate simultaneous search. This idea is known as fractional cascading in the data structures literature [8] The H tree scheme, however, offers no good performance guarantees for querying and in addition, the update algorithm ....

C. C. Low, B. C. Ooi & H. Lu, "H-trees: A Dynamic Associative Search Index for OODB," Proc. ACM SIGMOD (1992).

....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 queries. in [19] and more recently in [22], but the solutions offered there are largely heuristic with poor worst case performance. In Section 2.2, we reduce indexing classes to a special case of external dynamic 2 dimensional range searching called 3 sided searching. 3 sided range queries are a special case of 2 dimensional range ....

C. C. Low, B. C. Ooi, and H. Lu, "H-trees: A Dynamic Associative Search Index for OODB," Proc. ACM SIGMOD (1992), 134--143.

....that answering 3 sided queries efficiently is key to solving the problem of indexing classes. Indexing classes is the natural generalization of indexing in the context of objectoriented databases and is very important to their good performance (see [KiL, ZdM] for more information on this area) [KKD, LOL] present solutions to the problem of indexing classes. However, their algorithms are based on heuristics and cannot guarantee good worst case performance. Previous attempts to answer 3 sided queries in secondary memory by implementing priority search trees in secondary memory [IKO, KRV] did not ....

C. C. Low, B. C. Ooi, and H. Lu, "H-trees: A Dynamic Associative Search Index for OODB," Proc. ACM SIGMOD (1992), 134--143.

....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 [24] it constitutes the basis for indexing in object oriented databases. Indexing classes has been examined in [20] and more recently in [23], but the solutions offered there are largely heuristic with poor worst case performance. We assume in this paper that the class subclass relationship is static, although objects can be inserted to or deleted from classes. Under this reasonable assumption, we show in Section 2.2 that indexing ....

C. C. Low, B. C. Ooi, and H. Lu, "H-trees: A Dynamic Associative Search Index for OODB," Proc. ACM SIGMOD (1992), 134--143.

....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. C. Low, B. C. Ooi, and H. Lu, "H-trees: A Dynamic Associative Search Index for OODB," Proc. ACM SIGMOD (1992), 134--143.

....hierarchy [16] However, the study in [16] is confined to single level indexes for primitive attributes of a class without considering nested attributes. H trees is a hierarchical indexing organization supporting efficient associative search on objects based on the inheritance hierarchy [23]. The organization is tailored to supporting object retrieval from a single class as well as from an inheritance hierarchy of classes. The H tree indexes of the classes are structured in accordance with the inheritance hierarchy. A B tree is created for each class. The nested indexes are ....

C.C. Low, B.C. Ooi & H. Lu, "H-trees: a dynamic associative search index for OODB," Proceedings of the 1992 SIGMOD Conference, San Diego, CA, June 1992, 134--143.

....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 [MaS] it constitutes the basis for indexing in object oriented databases. Indexing classes has been examined in [KKD] and more recently in [LOL], but the solutions offered there are largely heuristic with poor worst case performance. In Section 2.2, we reduce indexing classes to a special case of external dynamic 2dimensional range searching. We also assume that the class subclass relationship is static, although objects can be inserted ....

C. C. Low, B. C. Ooi, and H. Lu, "H-trees: A Dynamic Associative Search Index for OODB," Proc. ACM SIGMOD (1992), 134--143.

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