1818982
Chained declustering: a new availability strategy for multiprocessor database machines
A new strategy for increasing the availability of data in multiprocessor, shared-nothing database machines is presented. This technique, termed chained declustering, is demonstrated to provide superior performance in the event of failures while maintaining a very high degree of data availability. Furthermore, unlike most earlier replication strategies, the implementation of chained declustering requires no special hardware and only minimal modifications to existing software.<<ETX>>
7196669
DIRECT - a multiprocessor organization for supporting relational data base management systems
The design of DIRECT, a multiprocessor organization for supporting relational data base management systems is presented. DIRECT has a MIMD (multiple instruction stream, multiple data stream) architecture. It can simultaneously support both intra-query and inter-query concurrency. The number of processors assigned to a query is dynamically determined by the priority of the query and the size of the relations it references. The size of a relation is not limited to that of the associative memory as in some previous data base machines. Concurrent updates are controlled through address translation tables which are maintained by a controlling processor.
 DIRECT is being implemented using LSI-11/03 microprocessors and CCD memories which are searched in an associative manner. A novel cross-point switch is used to connect the LSI-11 processors to the CCD memories. While cross-point switches have proven too expensive for use in general purpose parallel processors, their application in DIRECT demonstrates that these switches can be successfully used in specialized applications.
12861667
A performance analysis of the gamma database machine
This paper presents the results of an initial performance evaluation of the Gamma database machine. In our experiments we measured the effect of relation size and indices on response time for selection, join, and aggregation queries, and single-tuple updates. A Teradata DBC/1012 database machine of similar size is used as a basis for interpreting the results obtained. We also analyze the performance of Gemma relative to the number of processors employed and study the impact of varying the memory size and disk page size on the execution time of a variety of selection and join queries. We analyze and interpret the results of these experiments based on our understanding of the system hardware and software, and conclude with an assessment of the strengths and weaknesses of Gamma.
12442104
A performance evaluation of four parallel join algorithms in a shared-nothing multiprocessor environment
In this paper we analyze and compare four parallel join algorithms. Grace and Hybrid hash represent the class of hash-based join methods, Simple hash represents a looping algorithm with hashing, and our last algorithm is the more traditional sort-merge. The performance of each of the algorithms with different tuple distribution policies, the addition of bit vector filters, varying amounts of main-memory for joining, and non-uniformly distributed join attribute values is studied. The Hybrid hash-join algorithm is found to be superior except when the join attribute values of the inner relation are non-uniformly distributed and memory is limited. In this case, a more conservative algorithm such as the sort-merge algorithm should be used. The Gamma database machine serves as the host for the performance comparison.
1837093
Managing Intra-operator Parallelism in Parallel Database Systems
Int#ra-operator (or partitioned) parallelism is a well-established mechanism for achieving high performance in parallel database systems. However, the problem of how to exploit intra-operator parallelism in a multi-query environment is not well underst,ood. This paper presents a detailed performance evaluation of several algorithms for managing intra-operator parallelism in a parallel database system. A dynamic scheme based on the concept of matching the ra.te of flow of tuples between operat,ors is shown to perform well on a variety of workloads and configurations.
7889988
Crash recovery in client-server EXODUS
In this paper, we address the correctness and performance issues that arise when implementing logging and crash recovery in a page-server environment. The issues result from two characteristics of page-server systems: 1) the fact that data is modified and cached in client database buffers that are not accessible by the server, and 2) the performance and cost trade-offs that are inherent in a client-server environment. We describe a recovery system that we have implemented for the client-server version of the EXODUS storage manager. The implementation supports efficient buffer management policies, allows flexibility in the interaction between clients and the server, and reduces the server load by generating log records at clients. We also present a preliminary performance analysis of the implementation.
47273563
The Object-Oriented Database System Manifesto
This paper attempts to define an object-oriented database system. It describes the main features and characteristics that a system must have to qualify as an object-oriented database system. 
 
We have separated these characteristics into three groups: 
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Mandatory, the ones the system must satisfy in order to be termed an object-oriented database system. These are complex objects, object identity, encapsulation, types or classes, inheritance, overriding combined with late binding, extensibility, computational completeness, persistence, secondary storage management, concurrency, recovery and an ad hoc query facility. 
 
• 
Optional, the ones that can be added to make the system better, but which are not mandatory. These are multiple inheritance, type checking and inferencing, distribution, design transactions and versions. 
 
• 
Open, the points where the designer can make a number of choices. These are the programming paradigm, the representation system, the type system, and uniformity. 
 
 
 
 
We have taken a position, not so much expecting it to be the final word as to erect a provisional landmark to orient further debate.