The need for incremental algorithms for evaluating database queries is well known, but constructing algorithms that work on object-oriented databases (OODBs) has been difficult. The reason is that OODB query languages...
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The need for incremental algorithms for evaluating database queries is well known, but constructing algorithms that work on object-oriented databases (OODBs) has been difficult. The reason is that OODB query languages involve complex data types including composite objects and nested collections. As a result, existing algorithms have limitations in that the kinds of database updates are restricted, the operations found in many query languages are not supported, or the algorithms axe too complex to be described precisely. We present an incremental computation algorithm that can handle any kind of database updates, can accept any expressions in complex query languages such as OQL, and can be described precisely. By translating primitive values and records into collections, we can reduce all query expressions into ones composed of only one kind of operation, namely comprehension. This makes the problems with incremental computation less complicated and thus allows us to describe the algorithm precisely. Our incremental algorithm consists of two parts: one is to maintain the consistency in each comprehension occurrence and the other is to update the value of an entire expression. The algorithm is so flexible that we can use strict updates, lazy updates, and their combinations. By comparing the performance of applications built with our mechanism and that of equivalent hand written update programs, we show that our incremental algorithm can be implemented efficiently.
作者：
Hiroaki NakamuraIBM Research
Tokyo Research Laboratory 1623-14 Shimotsuruma Yamato-shi Kanagawa-ken 242-8502 Japan
The need for incremental algorithms for evaluating database queries is well known, but constructing algorithms that work on object-oriented databases (OODBs) has been difficult. The reason is that OODB query languages...
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ISBN:
(纸本)1581133359
The need for incremental algorithms for evaluating database queries is well known, but constructing algorithms that work on object-oriented databases (OODBs) has been difficult. The reason is that OODB query languages involve complex data types including composite objects and nested collections. As a result, existing algorithms have limitations in that the kinds of database updates are restricted, the operations found in many query languages are not supported, or the algorithms are too complex to be described precisely. We present an incremental computation algorithm that can handle any kind of database updates, can accept any expressions in complex query languages such as OQL, and can be described precisely. By translating primitive values and records into collections, we can reduce all query expressions comprehension. This makes the problems with incremental computation less complicated and thus allows us to decribe of two parts: one is to maintain the consistency in each comprehension occurrence and the other is to update the value of an entire expression. The algorithm is so flexible that we can use strict updates, lazy updates, and their combinations. By comparing the performance of applications built with our mechanism and that of equivalent hand written update programs, we show that our incremental algorithm can be iplemented efficiently.
The object-oriented programming language Java is an ideal companion to an object-oriented database system. This paper describes our approach to provide a seamless application programmer interface. it is based on a mod...
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ISBN:
(纸本)0818685859
The object-oriented programming language Java is an ideal companion to an object-oriented database system. This paper describes our approach to provide a seamless application programmer interface. it is based on a modular architecture with components for database engines, a communications protocol and a JAVA API faciltator: The open architecture is flexible, scalable and distributed in nature.
When implementing a multilevel security policy for object-oriented databases (OODBs), several aspects have to be investigated. One of these aspect is the design of multilevel OODBs. In an OODB, data are organized in a...
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ISBN:
(纸本)3540650040
When implementing a multilevel security policy for object-oriented databases (OODBs), several aspects have to be investigated. One of these aspect is the design of multilevel OODBs. In an OODB, data are organized in a complex structure built using different constructs (classes, objects, attributes, links...). Therefore, a first problem is to determine what constructs of the object-oriented model should be associated with a security level. A second problem is then to define semantics for each assignment of a security level to an object-oriented construct. While assigning the security levels, we have also to be careful with the inference problems which may occur due to the integrity constraints inherent in the object-oriented paradigm. Therefore, a last purpose of this paper is to define a set of general rules to cope with this problem.
Ordinary object-oriented databases have been well studied. We have already proposed a fuzzy object-oriented database that can treat fuzzy-set attribute values With certainly factors and fuzzy inheritance. In this pape...
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ISBN:
(纸本)078034863X
Ordinary object-oriented databases have been well studied. We have already proposed a fuzzy object-oriented database that can treat fuzzy-set attribute values With certainly factors and fuzzy inheritance. In this paper, we design and implement an SQL-type data manipulation language and demonstrate its facilities using several examples.
One of the differences between relational and object-oriented databases (OODB) is that attributes in OODB can be of a collection type (e.g. sets, lists, arrays, bags) as well as a simple type (e.g. integer, string). C...
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ISBN:
(纸本)0818683082
One of the differences between relational and object-oriented databases (OODB) is that attributes in OODB can be of a collection type (e.g. sets, lists, arrays, bags) as well as a simple type (e.g. integer, string). Consequently, explicit join queries in OODB may be based on collection attributes, One form of collection join queries in OODB is "collection-equi join queries", where the joins are based on collection attributes and the queries check for an equality of both collection operands. Our previous work [7] describes "Parallel Double Sort-Merge" algorithm for collection-equi join queries. Since the publication, we realize that we have overlooked the complexity of collection merging in the algorithm. in this paper We not only present alternative solutions relating to the collection merging problem, but also introduce a new algorithm called "Parallel Sort-Hash" algorithm. The two algorithms play an important role in parallel object-oriented query processing. due to their superiority over the conventional join methods through relational division and intersection operators.
A new publishing tool using the concept of hypertext views for object-oriented databases is presented. With this tool, one can make the contents of a database accessible through a Web interface to data browsing tools ...
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Horizontal partitioning (HP) technique is a logical database design technique first developed for distributed relational (record structured) databases. Though the main objective of HP is to reduce irrelevant data acce...
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Partial replication is a well established technique for relational databases. The creation of partial replica of object-oriented databases is more complex due to the richer type schema and object references. We presen...
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Multimedia databases include many types of new data. One common property of these data items is that they are very large. We exploit the concept of transformational representations to logically store images without th...
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