Atomic broadcast and failure detection are powerful primitives for distributed database systems In the distributed database system LAMBDA, they are provided as network primitives In this paper, we show how atomic broadcast and failure detection simplify transaction commitment, concurrency control, and crash recovery Specifically, we give a simple two-phase non-blocking commit protocol, whereas three phases are required in a point-to-point network We also give a simplified read-one/write-all update algorithm for replicated data and an easily implemented log-based recovery algorithm providing uninterrupted transaction processingThe benefits of performing the atomic broadcast and failure detection at the network level are also discussed Performing these functions at the network level not only simplifies database protocols but also better utilizes the broadcast network fewer messages are transmitted Comparisons between LAMBDA and existing distributed database systems are also made

A reliable broadcast protocol for an unreliable broadcast network is described.The protocol operates between the application programs and the broadcast network.It isolates the application programs from the unreliable characteristics of the communication network.The protocol guarantees that all of the broadcast messages are received at all of the operational receivers in a broadcast group.In addition, the sequence of messages is the same at each of the receivers and a total ordering exists among all broadcast messages.This unique message sequencing can be used to simplify distributed database systems and distributed processing algorithms.The protocol can operate with as few as one acknowledgment message per broadcast message, instead of one acknowledgment from each receiver per broadcast message.The protocol continues to operate when sites in the broadcast group fail.

In this paper the authors approach the problem of office activities management from the database viewpoint. Database alerting techniques are developed to serve the purpose of office activities management. A conceptual framework for office information system design is presented. Simple database alerters and implementation techniques, existential alerters and time alerters are discussed. An example of journal editing is described in detail. Finally, alerter system stability is discussed.

The problem of performing multiple attribute clustering in a dynamic database is studied. The extended K-d tree method is presented. In an extended K-d tree organization, the basic k-d tree structure after modification is used as the structure of the directory which organizes the data records in the secondary storage. The discriminator value of each level of the directory determines the partitioning direction of the corresponding attribute subspace. When the record insertion causes the data page to overload, the attribute space will be further partitioned along the direction specified by the corresponding discriminator.

In this study, a technique of performing multiple attribute clustering in dynamic databases has been investigated. We have transformed the problem of performing multiple attribute clustering into a problem of dynamically partitioning the attribute space. The optimal number of partitioning of the attribute space in a dynamic database environment has been analyzed, the partitioning direction is controlled by a discriminator sequence. The design of the discriminator sequence to obtain the optimal partitioning is presented. The selection of the directory attributes has also been discussed. Using the extended K-d tree to direct the partitioning, we have presented the extended K-d tree method. Empirical results have justified the improvement of the performance using the extended K-d tree method, when compared with that using the single attribute clustering or using inverted file method without any clustering index.

The problem of performing multiple attribute clustering in a dynamic database is studied. The extended K-d tree method is presented. in an extended K-d tree organization, the basic k-d tree structure after modification is used as the struc ture of the directory which organizes the data records in the secondary storage. The discrimina tor value of each level of the directory determines the partitioning direction of the corresponding attribute subspace. When the record insertion causes the data page to overload, the attribute space will be further partitioned along the direction specified by the corresponding discriminator. For a given query, the number of disk accesses involved is estimated. The design of the discriminator function are then described.