[1991] Proceedings. Seventh International Conference on Data Engineering

8-12 April 1991

Filter Results

Displaying Results 1 - 25 of 78
  • A framework for schema updates in an object-oriented database system

    Publication Year: 1991, Page(s):2 - 13
    Cited by:  Papers (16)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (796 KB)

    A 'reasonable' minimal set of primitives for updating an object-oriented (O/sub 2/) database schema is defined and the problems which need to be solved in order to obtain a usable schema update mechanism are shown. The distinction between structural and behavioral consistency for the O/sub 2/ system is described in some detail and it is demonstrated how updates could be performed by invoking an in... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • How spacey can they get? Space overhead for storage and indexing with object-oriented databases

    Publication Year: 1991, Page(s):14 - 22
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (579 KB)

    The impact of physical storage model choice on the performance of an object-oriented database is studied. It is examined how each of six physical storage models' space overhead reacts to changes in database parameters such as directed acrylic graph (DAG) shape, number of instances per class, and distribution of instances over the DAG. Home-class, leaf-overlap, and split-instance physical models co... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An association algebra for processing object-oriented databases

    Publication Year: 1991, Page(s):23 - 32
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (936 KB)

    An association algebra (A-algebra) is presented for manipulating object-oriented (O-O) databases which is analogous to the relational algebra for relational databases. In this algebra, objects and their associations in an O-O database are uniformly represented by association patterns and are manipulated by a number of operators. These operators are defined to operate on association patterns of bot... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Efficiently maintaining availability in the presence of partitionings in distributed systems

    Publication Year: 1991, Page(s):34 - 41
    Cited by:  Papers (9)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (737 KB)

    A new approach is presented for handling partitionings in replicated distributed databases. Mechanisms are developed through which transactions can access replicated data objects and observe delays similar to nonreplicated systems while enjoying the availability benefits of replication. The replication control protocol, called VELOS, achieves optimal availability, according to a well-known metric,... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Processing of multiple processing queries in distributed databases

    Publication Year: 1991, Page(s):42 - 49
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (577 KB)

    A set of algorithms is described that can be used to reduce the complexity of evaluating multiple queries of a transaction in a distributed environment. With the consideration of conjunct sharing, it compiles a set of queries into a network based on the concept of semijoins. As some of the queries in a transaction may change the contents of a database, evaluation of the network corresponding to th... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Determining beneficial semijoins for a join sequence in distributed query processing

    Publication Year: 1991, Page(s):50 - 58
    Cited by:  Papers (1)  |  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (683 KB)

    The problem of combining join and semijoin reducers for distributed query processing is studied. An approach, of interleaving a join sequence with beneficial semijoins is proposed. A join sequence is mapped into a join sequence tree that provides an efficient way to identify for each semijoin its correlated semijoins as well as its reducible relations under the join sequence. In light of these pro... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Interactive manipulation of object-oriented views

    Publication Year: 1991, Page(s):60 - 69
    Cited by:  Papers (2)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (645 KB)

    An approach to providing view support in object-oriented (O/sub 2/) databases is presented. The approach uses what is called a hyper-view and combines results from research on database design and man-machine interfaces. A mechanism that allows interacting with databases through hyper-views and built on top of the O/sub 2/ system is described. The approach is based on conciliating stored data and t... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Implementation and evaluation of a browsing algorithm for design applications

    Publication Year: 1991, Page(s):70 - 79
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (665 KB)

    The implementation and evaluation of an extended relational database called ADAM (advanced database abstraction mechanism) are discussed. A browsing algorithm is developed for composite objects to support reuse of the objects. The algorithm takes advantage of aggregation hierarchies to select related composite objects and to order them based on the two measures, i.e. the relative difference of mat... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A knowledge-based subsystem for a natural language interface to a database that predicts and explains query failures

    Publication Year: 1991, Page(s):80 - 87
    Cited by:  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (659 KB)

    A practical method is presented for eliminating unnecessary database operations that often arise from poorly posed natural language queries. This subsystem consists mainly of a knowledge-base whose rules are semantic constraints of the database. The inference procedure's actions are, unlike that of similar inference engines, strictly controlled by the structure of the query. Because of this it is ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Wait depth limited concurrency control

    Publication Year: 1991, Page(s):92 - 101
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (794 KB)

    A new class of wait depth limited (WDL) concurrency control (CC) methods is described. The WDL policy is shown by simulations to be effective both in systems with proportionately large I/O latencies as well as in systems with large numbers of processors. WDL is also attractive in terms of implementation. In many applications little or no system modification may be required other than the CC code. ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Efficient implementation techniques for the time index

    Publication Year: 1991, Page(s):102 - 111
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (613 KB)

    A new indexing technique, time index, for improving the performance of certain classes of temporal queries was previously described by the author (see The 16th Conference on Very Large Databases (1990)). Three variations for implementing the time index efficiently are proposed and the performance of these three variations is compared with the performance of the original time index. Various paramet... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Voting with regenerable volatile witnesses

    Publication Year: 1991, Page(s):112 - 119
    Cited by:  Papers (4)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (594 KB)

    Voting protocols ensure the consistency of replicated objects by requiring all read and write requests to collect an appropriate quorum of replicas. It is proposed to replace some of these replicas with volatile witnesses that have no data and require no stable storage, and to regenerate them instead of waiting for recovery. The small size of volatile witnesses allows them to be regenerated much e... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modeling uncertainty in databases

    Publication Year: 1991, Page(s):122 - 131
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (567 KB)

    Relational algebra operations were extended to produce, together with answers to queries, information regarding sources that contributed to the answers. The author's previous model is reviewed and the semantic interpretation is presented. It is shown that extended relational algebra operations are precise, that is, they produce exactly the same answers that are expected under the semantic interpre... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Natural joins in relational databases with indefinite and maybe information

    Publication Year: 1991, Page(s):132 - 139
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (509 KB)

    Natural joins are defined, in a semantically correct way, on data structures, called I-tables, of an extended relational database model with indefinite and maybe information. An algorithm for computing natural joins under the extended model is proposed which reduces the number of pair-up operations and block accesses to a linear order of complexity with respect to the size of I-tables. Procedures ... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Meta-reasoning: An incremental compilation approach

    Publication Year: 1991, Page(s):140 - 149
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (662 KB)

    An incremental compilation approach to meta-reasoning is presented together with a method to update dynamically changing knowledge bases. The compilation process translates meta-level specification of facts and hypotheses into sentences of clausal logic. It then incrementally computes inconsistent sets of instances of hypotheses and records potential crucial literals. The extra information compute... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An indexing techniques for object-oriented databases

    Publication Year: 1991, Page(s):160 - 170
    Cited by:  Papers (18)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (937 KB)

    The basic characteristics of object-oriented data models and query languages are summarized. An indexing technique is presented that supports an efficient evaluation of nested predicates for queries involving class hierarchies. A preliminary comparison of the proposed indexing technique with other techniques is presented. A first extension of this work is to define cost formulas for the proposed i... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An efficient hybrid join algorithm: a DB2 prototype

    Publication Year: 1991, Page(s):171 - 180
    Cited by:  Papers (14)  |  Patents (22)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (826 KB)

    A new join method, called hybrid join, is proposed which uses the join-index filtering and the skip sequential prefetch mechanism for efficient data access. With this method, the outer table is sorted on the join column. Then, the outer is joined with the index on the join column of the inner. The inner tuple is represented by its surrogate, equivalent of its physical disk address, which is carrie... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Navigation and schema transformations for producing nested relations from networks

    Publication Year: 1991, Page(s):181 - 190
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (717 KB)

    Efficient procedures for producing nested relations from networks are considered. Various types of nested relations are defined according to the interaction between the networks' and nested relations' schemas. Among these types, partitional normal form (PNF) and accordant nested relations are shown to be produced by an extended navigation, called touch information display (TID) navigation, which r... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Parallel computation of direct transitive closures

    Publication Year: 1991, Page(s):192 - 199
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (516 KB)

    To efficiently process recursive queries in a DBMS (database management system), a parallel, direct transitive closure algorithm is proposed. Efficiency is obtained by reorganizing the computation order of Warren's algorithm. The number of transfers among processors depends only on the number of processors and does not depend on the depth of the longest path. The evaluation shows an improvement du... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An effective algorithm for parallelizing hash joins in the presence of data skew

    Publication Year: 1991, Page(s):200 - 209
    Cited by:  Papers (21)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (969 KB)

    A parallel hash join algorithm based on the concept of hierarchical hashing is proposed to address the problem data skew. The proposed algorithm adds an extra scheduling phase to the usual hash and join phases. During the scheduling phase, a heuristic optimization algorithm, using the output of the hash phase, attempts to balance the load across the multiple processors in the subsequent join phase... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Scheduling batch transactions on shared-nothing parallel database machines: effects of concurrency and parallelism

    Publication Year: 1991, Page(s):210 - 219
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (802 KB)

    Concurrency-control scheduling of batch transactions on shared-nothing (or loosely-coupled) multiprocessor database machines is discussed. Various schedulers are tested for these batch transactions to examine how well they perform when both intertransaction parallelism and intratransaction parallelism are limited. New schedulers designed for batch transaction processing are outlined which use a ne... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • The software architecture of a parallel processing system for advanced database applications

    Publication Year: 1991, Page(s):220 - 229
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (824 KB)

    A parallel processing scheme and software architecture of SMASH, a parallel processing system for supporting a wide variety of database applications is presented. The main feature of this system is that functional programming concepts are applied to define new database operations and data types and to exploit parallelism inherent in an arbitrary set of database operations. A primitive set (SMASH p... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Semantic query reformulation in deductive databases

    Publication Year: 1991, Page(s):232 - 239
    Cited by:  Papers (3)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (713 KB)

    A method is proposed for identifying relevant integrity constraints (ICs) for queries involving joins/unions of base relations and defined relations by use of graphs. The method does not rely on heavy preprocessing or redundancy. To effectively select those ICs that are relevant to a given query, the relationship between the predicates in the query is identified using an AND/OR tree where an AND m... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Design overview of the Aditi deductive database system

    Publication Year: 1991, Page(s):240 - 247
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (689 KB)

    An overview of the structure of Aditi, a disk-based deductive database system under continuous development at the University of Melbourne, is presented. The aim of the project is to find out what implementation methods and optimization techniques would make deductive databases competitive with current commercial relational databases. The structure of the Aditi prototype is based on a variant of th... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A rule-based query rewriter in an extensible DBMS

    Publication Year: 1991, Page(s):248 - 256
    Cited by:  Papers (1)  |  Patents (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (770 KB)

    An integrated approach to query rewriting in an extensible database server supporting ADTs, objects, deductive capabilities and integrity constraints is described. The approach is extensible through a uniform high level rule language used by the database implementor to specify optimization techniques. This rule language is compiled to enrich the strategy component and the knowledge base of the rew... View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.