W.C. Lee and D.L. Lee. Signature file methods for indexing object-oriented database systems. In Proc. of the 2nd Int. Computer Science Conf., pages 616--622, Hong Kong, 1992.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....proposed for indexing set valued data and, when used with signatures, they exhibit similar performance to that of S trees [22] Besides inclusive queries, 23] examines the performance of signature based structures for set valued objects under the join query with subset superset predicates. In [24, 25, 26], the use of signatures in path expressions has been also studied. In the present paper, we focus on optimizing S trees, which have been widely cited in previous works reporting performance comparisons with other structures. However, in the past, S trees have been used under their original ....

Lee, W. C. and Lee, D. L. (1992) Signature file methods for indexing object-oriented database systems. Proc. 2nd Computer Science Conf., Hong Kong, pp. 616--622.

....a query. The corresponding data items are then checked and all false drops are eliminated. We describe each index structure generally and also give details about storage costs and retrieval update costs. We begin with the Sequential signature file and Russian Doll tree, which are already known [LL92], IKO93] HP94] The two new index structures are 10 based on extendible hashing [FNPS79] and recursive linear hashing [RSD84] which we describe briefly. We then explain how to adapt those index structures to support queries with set predicates. When looking at the costs for the index ....

....3.1 Sequential signature files 3.1. 1 General description [sig(o 1 ) ref(o 1 ) sig(o 2 ) ref(o 2 ) sig(o n ) ref(o n ) Figure 4: Sequential signature file index structure (SSF) The sequential signature file (SSF) method is a simple way to index data items using signatures [LL92], IKO93] Signature files have entries in the form of a tuple [sig(o i ) ref(o i ) containing the signature sig(o i ) of an indexed data item o i and an unique identifier ref(o i ) with which the data item can be accessed. The signatures and identifiers of all data items o i , 1 i n are ....

W.C. Lee and D.L. Lee. Signature file methods for indexing object-oriented database systems. In Proc. of the 2nd Int. Computer Science Conf., pages 616--622, Hong Kong, 1992.

.... files were originally designed for text retrieval [4] 6] 8] Although applications of signature files to non text object retrieval, such as to the traditional record retrieval [7] 17] 18] to the Prolog clause retrieval [21] and to the object navigation in the objectoriented database [14], 22] were discussed, study focusing on their use in set retrieval has not been reported by other researchers. Retrieval with signature files is always accompanied by mismatches called false drops. The number of false drops has a direct effect on the performance [10] Therefore, it is important ....

W.-c. Lee and D. L. Lee, "Signature file methods for indexing object-oriented database systems," in Proc. Intl. Computer Science Conf. (ICSC), Hong Kong, 1992, pp. 616--622.

....becomes bidirectional, resulting in no difference between the top down and the bottom up approaches. In this paper, however, we assume there is no inverse references. There are many kinds of nested queries, and several indexing organizations have been proposed to support nested query processing [1,2,6,7,9]. However, an access method doesn t necessarily support all of the nested queries. Even with the same access method, different kinds of queries may be evaluated differently. To facilitate our discussion, we define target classes as the classes from which objects are retrieved and predicate ....

.... signature scheme creates the signature of an object by superimposing the signatures of all of the simple and nested attributes of the object in the aggregation hierarchy, whereas the path signature method generates an object signature based on the simple and nested attributes along a given path [7]. The signature replication technique [9] generates object signatures from the simple attribute values of the objects. Instead of using only OIDs, the object signature of an object and its OID are stored as complex attributes of the parent objects. Moreover, a signature technique for the support ....

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W.-C. Lee & D.L. Lee, "Signature File Methods for Indexing Object-Oriented Database Systems," Proceedings of the 2nd International Computer Science Conference, Hong Kong, Dec. 1992, 616--622.

....resulting in no difference between the top down and the bottom up approaches. In this paper, however, we assume there is no inverse references. Many access methods have been proposed to support the complex queries in OODBSs. In particular, three techniques, namely, indexing [1,2,3] signature file [4,7] and path dictionary [6] have been proposed recently. A similar idea to path dictionary has also been used in [5] In this paper, we further develop our previous implementation of the path dictionary approach [6] and combine it with index The author is on leave from the Department of ....

....the path dictionary, the indexes support rapid access to s expressions in the path dictionary, thus dramatically improving update as well as retrieval performance at the cost of only a small increase in storage overhead. Path = Person.Vehicle.Company Company[1] Vehicle[5] Person[3] Person[7]) Vehicle[12] Person[4] Company[2] Vehicle[6] Vehicle[9] Vehicle[11] Company[3] Vehicle[3] Company[4] Vehicle[4] Vehicle[7] Person[1] Person[6] Person[9] Company[5] Vehicle[1] Person[2] Vehicle[2] Person[8] Person[12] Vehicle[8] Person[5] Vehicle[10] Figure 2: ....

[Article contains additional citation context not shown here]

W.-C. Lee & D.L. Lee, "Signature File Methods for Indexing Object-Oriented Database Systems," Proceedings of the 2nd International Computer Science Conference, Hong Kong, Dec. 1992, 616--622.

....On the other hand, the top down approach may choose a depth first style of forward traversal which doesn t require much internal memory. Many access methods have been proposed to support complex queries in OODBSs. In particular, three techniques, namely, indexing [2,3,5,24] signature file [9,21,28] and data dictionary [19,20] have been proposed recently. In this paper, we discuss the problems with query processing in OODBSs and present the path dictionary organization. The rest of the paper is organized as follows. Section 2 summarizes the access methods proposed in the literature. Section ....

....forward traversals (i.e. PT queries) and queries involving a large number of the attributes. The latter is because values from many attributes, not just one attribute, are encoded in the signatures. Tree signature and path signature are two of the signature file schemes proposed by the authors [21]. The tree signature scheme generates the signature of an object by hashing all of its direct and nested primitive attributes into a signature. Therefore, the signature is an abstraction of information directly stored or nested in the object. The path signature scheme generates the signature of an ....

W.-C. Lee & D.L. Lee, "Signature File Methods for Indexing Object-Oriented Database Systems, " Proceedings of the 2nd International Computer Science Conference, Hong Kong, Dec. 1992, 616--622.

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W.C. Lee and D.L. Lee. Signature file methods for indexing object-oriented database systems. In Proc. of the 2nd Int. Computer Science Conf., pages 616--622, Hong Kong, 1992.

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