Proceedings of 1994 IEEE 10th International Conference on Data Engineering

14-18 Feb. 1994

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Displaying Results 1 - 25 of 56
  • A query sampling method for estimating local cost parameters in a multidatabase system

    Publication Year: 1994, Page(s):144 - 153
    Cited by:  Papers (14)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (863 KB)

    In a multidatabase system (MDBS), some query optimization information related to local database systems may not be available at the global level because of local autonomy. To perform global query optimization, a method is required to derive the necessary local information. This paper presents a new method that employs a query sampling technique to estimate the cost parameters of an autonomous loca... View full abstract»

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  • Cooperative problem solving using database conversations

    Publication Year: 1994, Page(s):134 - 143
    Cited by:  Papers (2)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1004 KB)

    Cooperative problem solving is a joint style of producing and consuming data. Unfortunately, most database mechanisms developed so far; are more appropriate for competitive usage than for a cooperative working style. They mostly adopt an operational point of view which binds data to applications. Data-oriented mechanisms like check-in/out avoid this binding but do not improve synchronization towar... View full abstract»

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  • Storage reclamation and reorganization in client-server persistent object stores

    Publication Year: 1994, Page(s):120 - 131
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1055 KB)

    The authors develop and evaluate a number of storage reclamation algorithms for client-server persistent object stores. Experience with a detailed simulation and a prototype implementation in the Exodus storage manager shows that one of the proposed algorithms, the Incremental Partitioned Collector, is complete, maintains transaction semantics, and can be run incrementally and concurrently with cl... View full abstract»

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  • Performance analysis of RAIDS disk arrays with a vacationing server model for rebuild mode operation

    Publication Year: 1994, Page(s):111 - 119
    Cited by:  Papers (14)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (892 KB)

    We analyze the performance of RAIDS disk arrays in normal, degraded, and rebuild modes. The analysis, which is shown to be highly accurate through validation against simulation results, achieves its accuracy by (1) modeling detailed disk characteristics; (2) developing a simple approximation to compute the mean response time for fork-join requests arising in degraded mode operation; and (3) using ... View full abstract»

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  • Analysis of reorganization overhead in log-structured file systems

    Publication Year: 1994, Page(s):102 - 110
    Cited by:  Papers (5)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (717 KB)

    In a log-structured file system (LFS), in general each block written to disk causes another disk block to become invalid data, resulting in one block of free space. Over time free disk space becomes highly fragmented, and a high level of dynamic reorganization may be required to coalesce free blocks into physically contiguous areas that subsequently can be used for logs. By consuming available dis... View full abstract»

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  • Performing group-by before join /spl lsqb/query processing/spl rsqb/

    Publication Year: 1994, Page(s):89 - 100
    Cited by:  Papers (8)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (936 KB)

    Assume that we have an SQL query containing joins and a group-by. The standard way of evaluating this type of query is to first perform all the joins and then the group-by operation. However, it may be possible to perform the group-by early, that is, to push the group-by operation past one or more joins. Early grouping may reduce the query processing cost by reducing the amount of data participati... View full abstract»

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  • A multi-set extended relational algebra: a formal approach to a practical issue

    Publication Year: 1994, Page(s):80 - 88
    Cited by:  Papers (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (690 KB)

    The relational data model is based on sets of tuples, i.e. it does not allow duplicate tuples an a relation. Many database languages and systems do require multi-set semantics though, either because of functional requirements or because of the high costs of duplicate removal in database operations. Several proposals have been presented that discuss multi-set semantics. As these proposals tend to b... View full abstract»

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  • Exploiting uniqueness in query optimization

    Publication Year: 1994, Page(s):68 - 79
    Cited by:  Papers (2)  |  Patents (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1092 KB)

    Consider an SQL query that specifies duplicate elimination via a DISTINCT clause. Because duplicate elimination often requires an expensive sort of the query result, it is often worthwhile to identify unnecessary DISTINCT clauses and avoid the sort altogether. We prove a necessary and sufficient condition for deciding if a query requires duplicate elimination. The condition exploits knowledge abou... View full abstract»

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  • Mariposa: a new architecture for distributed data

    Publication Year: 1994, Page(s):54 - 65
    Cited by:  Papers (29)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1231 KB)

    We describe the design of Mariposa, an experimental distributed data management system that provides high performance in an environment of high data mobility and heterogeneous host capabilities. The Mariposa design unifies the approaches taken by distributed file systems and distributed databases. In addition, Mariposa provides a general, flexible platform for the development of new algorithms for... View full abstract»

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  • Efficient support for partial write operations in replicated databases

    Publication Year: 1994, Page(s):43 - 53
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1248 KB)

    We present a new replica control technique targeted at replicated systems in which write operations update a portion of the information in the data item rather than replacing it entirely. The existing protocols capable of supporting partial writes must either perform the writes on all accessible replicas of the data item, or always apply the writes to the same group (quorum set) of replicas. In th... View full abstract»

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  • Supporting partial data accesses to replicated data

    Publication Year: 1994, Page(s):32 - 42
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (999 KB)

    Partial data access operations occur frequently in distributed systems. This paper presents new approaches for efficiently supporting partial data access operations to replicated data. We propose the replica modularization (RM) technique which suggests partitioning replicas into modules, which now become the minimum unit of data access. RM is shown to increase the availability of both partial read... View full abstract»

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  • Object allocation in distributed databases and mobile computers

    Publication Year: 1994, Page(s):20 - 29
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (999 KB)

    This paper makes two contributions. First, we introduce a model for evaluating the performance of data allocation and replication algorithms in distributed databases. The model is comprehensive in the sense that it accounts for I/O cost, for communication cost, and for limits on the minimum number of copies of the object (to ensure availability). The second contribution of this paper is the introd... View full abstract»

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  • Approximate analysis of real-time database systems

    Publication Year: 1994, Page(s):10 - 19
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (764 KB)

    During the past few years, several studies have been made on the performance of real-time database systems with respect to the number of transactions that miss their deadlines. These studies have used either simulation models or database testbeds as their performance evaluation tools. We present a preliminary analytical performance study of real-time transaction processing. Using a series of appro... View full abstract»

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  • On a more realistic lock contention model and its analysis

    Publication Year: 1994, Page(s):2 - 9
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (752 KB)

    Most performance modeling studies of lock contention in transaction processing systems are deficient in that they postulate a homogeneous database access model. The non-homogeneous database access model described in this paper allows multiple transaction classes with different access patterns to the database regions. The performance of the system from the viewpoint of lock contention is analyzed i... View full abstract»

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  • Proceedings of 1994 IEEE 10th International Conference on Data Engineering

    Publication Year: 1994
    Request permission for commercial reuse | PDF file iconPDF (82 KB)
    Freely Available from IEEE
  • Resolving attribute incompatibility in database integration: an evidential reasoning approach

    Publication Year: 1994, Page(s):154 - 163
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (903 KB)

    Resolving domain incompatibility among independently developed databases often involves uncertain information. DeMichiel (1989) showed that uncertain information can be generated by the mapping of conflicting attributes to a common domain, based on some domain knowledge. The authors show that uncertain information can also arise when the database integration process requires information not direct... View full abstract»

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  • Managing change in the Rufus system

    Publication Year: 1994, Page(s):170 - 179
    Cited by:  Papers (2)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (943 KB)

    Rufus is an information system that models user data with objects taken from a class system. Due to the importance of coping with changes to the schema, Rufus has adopted the conformity-based model of Melampus. This model enables Rufus to cope with schema changes more easily than traditional class- and inheritance-based data models. The paper reviews the Melampus data model and describes how it wa... View full abstract»

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  • Polymorphic reuse mechanisms for object-oriented database specifications

    Publication Year: 1994, Page(s):180 - 189
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (761 KB)

    A polymorphic approach to the incremental design and reuse of object-oriented methods and query specifications is presented. Using this approach, the effort required for manually reprogramming methods and queries due to schema modifications can be avoided or minimized. The salient features of of our approach are the use of propagation patterns and a mechanism for propagation pattern refinement. Pr... View full abstract»

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  • A method for transforming relational schemas into conceptual schemas

    Publication Year: 1994, Page(s):190 - 201
    Cited by:  Papers (23)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1040 KB)

    A major problem with currently existing database systems is that there often does not exist a conceptual understanding of the data. Such an understanding can be obtained by describing the data using a semantic data model, such as the ER model. Consequently, there is a need for methods that translate a schema in a traditional data model into a conceptual schema. We present a method for translating ... View full abstract»

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  • On the interaction between ISA and cardinality constraints

    Publication Year: 1994, Page(s):204 - 213
    Cited by:  Papers (11)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (841 KB)

    ISA and cardinality constraints are among the most interesting types of constraints in data models. ISA constraints are used to establish several forms of containment among classes, and are receiving great attention in moving to object-oriented data models, where classes are organized in hierarchies based on a generalization/specialization principle. Cardinality constraints impose restrictions on ... View full abstract»

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  • Comparing and synthesizing integrity checking methods for deductive databases

    Publication Year: 1994, Page(s):214 - 222
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (678 KB)

    We compare and synthesize different methods for integrity checking in deductive databases. First, we state simplified integrity checking for deductive databases independently of the particular strategy used by different methods found in the literature. In accordance with this statement, we classify integrity checking methods into two main groups: methods with a generation phase without fact access... View full abstract»

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  • Discovering database summaries through refinements of fuzzy hypotheses

    Publication Year: 1994, Page(s):223 - 230
    Cited by:  Papers (2)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (632 KB)

    Recently, many applications such as scientific databases and decision supporting systems that require comprehensive analysis of a very large amount of data, have been evolved. Summary discovery techniques, which extract compact representations grasping the meanings of large databases, can play a major role in those applications. We present an effective and robust method to discover simple linguist... View full abstract»

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  • Declustering techniques for parallelizing temporal access structures

    Publication Year: 1994, Page(s):232 - 242
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1089 KB)

    This paper addresses the issues of declustering temporal index and access structures for a single processor multiple independent disk architecture. The temporal index is the Monotonic B/sup +/-Tree which uses the time index temporal access structure. We devise a new algorithm, called multi-level round robin, for assigning tree nodes to multiple disks. The multi-level round robin declustering techn... View full abstract»

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  • Disk allocation methods for parallelizing grid files

    Publication Year: 1994, Page(s):243 - 252
    Cited by:  Papers (8)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1094 KB)

    The grid file is a well known access method for multi-dimensional and spatial data. The response time needed to process path and range queries on the grid file access method can be improved significantly by distributing the data pages over multiple disks. The paper explores the disk allocation methods used to allocate the data pages of grid file among a set of disks, which can be accessed in paral... View full abstract»

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  • Object placement in parallel object-oriented database systems

    Publication Year: 1994, Page(s):253 - 262
    Cited by:  Papers (3)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1044 KB)

    Parallelism is a viable solution to constructing high performance object-oriented database systems. In parallel systems based on a shared-nothing architecture, the database is horizontally declustered across multiple processors, enabling the system to employ multiple processors to speedup the execution time of a query. The placement of objects across the processors has a significant impact on the ... View full abstract»

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