Methods for creating and maintaining keysequence data sets without overwriting the storage medium... more Methods for creating and maintaining keysequence data sets without overwriting the storage medium are described. These methods may be applied to erasable or to write-once storage devices, and they are compatible with conventional device error-management techniques. All past values of data records are preserved in a data structure called a WriteOnce 6-Tree. Rapid random access is available to records by key value; rapid sequential access is available to records in key-sequence order. Moreover, queries requesting data as of a previous time are processed as rapidly as requests for current data. Access time is proportional to the logarithm of the number of current records in the database. Efficient methods for inserting, updating, and deleting records are described. Upper bounds for tree depth and for storage consumption are given and compared with results from simulation. It is concluded that, with rapidly improving storage technologies, indelible databases will become practical for ma...
Reiner@CCA UUCP: decvax!cca!reiner Database Engineering Bulletin is a quarterly publication of th... more Reiner@CCA UUCP: decvax!cca!reiner Database Engineering Bulletin is a quarterly publication of the IEEE Computer Society Technical Committee on Database Engineering. Its scope of interest includes: data structures and models, access strategies, access control techniques, database architecture, database machines, intelligent front ends, mass storage for very large databases, distributed database systems and techniques, database software design and implementation, database utilities, database security and related areas. Contribution to the Bulletin is hereby solicited. News items, letters, technical papers, book reviews, meeting previews, summaries, case studies, etc., should be sent to the Editor. All letters to the Editor will be considered for publication unless accompanied by a request to the contrary. Technical papers are unretereed. Opinions expressed in contributions are those of the indi vidual author rather than the official position of the TC on Database Engineering, the IEEE Computer Society, or orga nizations with which the author may be affiliated. Associate Editors, Database Engineering Dr. Haran Boral Microelectronics and Computer Technology Corporation (MCC) 9430 Research Blvd.
Abstract The batch throughput efficiency is studied for three variants on selective reject protoc... more Abstract The batch throughput efficiency is studied for three variants on selective reject protocols that operate in a full duplex asynchronous response mode and that adhere to the common architectural features of ADCCP, HDLC, and SDLC. In these architectures, the ...
In this note, an efficient method for weighted sampling of K objects without replacement from a ... more In this note, an efficient method for weighted sampling of K objects without replacement from a population of n objects is proposed. The method requires O(K log n) additions and comparisons, and O(K) multiplications and random number generations while the method proposed by Fagin and Price requires O(Kn) additions and comparisons, and O(K) divisions and random number generations.
Circumstances favoring the use of Monte Carlo methods for evaluating the reliability of large sys... more Circumstances favoring the use of Monte Carlo methods for evaluating the reliability of large systems are discussed. A new method, that of Sequential Destruction (SD) is introduced. The SD method requires no preparatory topological analysis of the system, and remains viable when element failure probabilities are small. It applies to a variety of reliability measures and does not require element failures to be s-independent. The method can be used to improve the performance of selective sampling techniques. Substantial variance reductions, as well as computational savings, are demonstrated using a sample system with more than 100 elements.
Methods for creating and maintaining keysequence data sets without overwriting the storage medium... more Methods for creating and maintaining keysequence data sets without overwriting the storage medium are described. These methods may be applied to erasable or to write-once storage devices, and they are compatible with conventional device error-management techniques. All past values of data records arepreserved in a data structure called a Write Once B-Tree. Rapid random access is available to records by key value; rapid sequential access is available to records in key-sequence order. Moreover, queries requesting data as of a previous time are processed as rapidly as requests for current data. Access time is proportional to the logarithm of the number of current records in the database. Efficient methods for inserting, updating, and deleting records are described. Upper bounds for tree depth and for storage consumption are given and compared with results from simulation. It is concluded that, with rapidly improving storage technologies, indelible databases will become practical for many applications.
In a two-level computer storage hierarchy, miss ratio measurements are often made from a "cold st... more In a two-level computer storage hierarchy, miss ratio measurements are often made from a "cold start", that is, made with the first-level store initially empty. For large capacities the effect on the measured miss ratio of the misses incurred while filling the first-level store can be significant, even for long reference strings. Use of "warm-start" rather than "cold-start" miss ratios cast doubt on the widespread belief that the observed "S-shape" of lifetime (reciprocal of miss ratio) versus capacity curve indicates a property of behavior of programs that maintain a constant number of pages in main storage. On the other hand, if cold-start miss ratios are measured as a function of capacity and measurement length, then they are useful in studying systems in which operation of a program is periodically interrupted by task switches. It is shown how to obtain, under simple assumptions, the cache miss ratio for multiprogramming from cold-start miss ratio values and how to obtain approximate cold-start miss ratios from warm-start miss ratios.
The design of selective-repeat retransmission protocols to provide reliable transfer of large dat... more The design of selective-repeat retransmission protocols to provide reliable transfer of large data files is discussed. The transmission system is assumed capable of losing, distorting, or reordering the transmitted data frames and acknowledgment frames. The principle design considerations center on methods for managing the finite sequence number space and methods for managing the finite-sized receiver buffer. Under the assumption that there exists a maximum time from transmission of a frame to receipt of an acknowledgment for that frame, methods are described for safe reuse of frame sequence numbers. Previous results by Metzner and Morgan on buffer overflow control are extended to cover non-FIFO transmission systems. A two-dimensional space of design parameters is explored by way of Monte Carlo simulations. For appropriate designs, it is shown that significant increases in throughput over that achieved by the Go-Back4 protocol are possible on high-rate long-delay channels. W 0090-6778/81/0700-0944$00.75 0 1981 IEEE
A retransmission protocol for a broadcast connection (point-to-multipoint) is proposed and its pe... more A retransmission protocol for a broadcast connection (point-to-multipoint) is proposed and its performance characteristics are considered. The protocol is designed for transfers of large files over a satellite channel that is time-shared to carry both the data from the broadcasting transmitter and the set of acknowledgments from the multiple receiver sites. A mathematical model of the transmission system that includes separate error processes for uplink and downlink errors on data transmission, and similar processes for errors on the acknowledgement frames as well, is used to analyze the performance of the scheme. Exact analytical expressions for the relative throughput of the channel are obtained for two special cases: (1) the uplink is error-free; and (2) the acknowledgments are error-free. For the general case, upper and lower bounds are derived and are shown to be virtually indistinguishable for many practical sets of system parameters. The results demonstrate that the broadcasting of large files to multiple receivers can be done both efficiently and reliably.
Methods for creating and maintaining keysequence data sets without overwriting the storage medium... more Methods for creating and maintaining keysequence data sets without overwriting the storage medium are described. These methods may be applied to erasable or to write-once storage devices, and they are compatible with conventional device error-management techniques. All past values of data records are preserved in a data structure called a WriteOnce 6-Tree. Rapid random access is available to records by key value; rapid sequential access is available to records in key-sequence order. Moreover, queries requesting data as of a previous time are processed as rapidly as requests for current data. Access time is proportional to the logarithm of the number of current records in the database. Efficient methods for inserting, updating, and deleting records are described. Upper bounds for tree depth and for storage consumption are given and compared with results from simulation. It is concluded that, with rapidly improving storage technologies, indelible databases will become practical for ma...
Reiner@CCA UUCP: decvax!cca!reiner Database Engineering Bulletin is a quarterly publication of th... more Reiner@CCA UUCP: decvax!cca!reiner Database Engineering Bulletin is a quarterly publication of the IEEE Computer Society Technical Committee on Database Engineering. Its scope of interest includes: data structures and models, access strategies, access control techniques, database architecture, database machines, intelligent front ends, mass storage for very large databases, distributed database systems and techniques, database software design and implementation, database utilities, database security and related areas. Contribution to the Bulletin is hereby solicited. News items, letters, technical papers, book reviews, meeting previews, summaries, case studies, etc., should be sent to the Editor. All letters to the Editor will be considered for publication unless accompanied by a request to the contrary. Technical papers are unretereed. Opinions expressed in contributions are those of the indi vidual author rather than the official position of the TC on Database Engineering, the IEEE Computer Society, or orga nizations with which the author may be affiliated. Associate Editors, Database Engineering Dr. Haran Boral Microelectronics and Computer Technology Corporation (MCC) 9430 Research Blvd.
Abstract The batch throughput efficiency is studied for three variants on selective reject protoc... more Abstract The batch throughput efficiency is studied for three variants on selective reject protocols that operate in a full duplex asynchronous response mode and that adhere to the common architectural features of ADCCP, HDLC, and SDLC. In these architectures, the ...
In this note, an efficient method for weighted sampling of K objects without replacement from a ... more In this note, an efficient method for weighted sampling of K objects without replacement from a population of n objects is proposed. The method requires O(K log n) additions and comparisons, and O(K) multiplications and random number generations while the method proposed by Fagin and Price requires O(Kn) additions and comparisons, and O(K) divisions and random number generations.
Circumstances favoring the use of Monte Carlo methods for evaluating the reliability of large sys... more Circumstances favoring the use of Monte Carlo methods for evaluating the reliability of large systems are discussed. A new method, that of Sequential Destruction (SD) is introduced. The SD method requires no preparatory topological analysis of the system, and remains viable when element failure probabilities are small. It applies to a variety of reliability measures and does not require element failures to be s-independent. The method can be used to improve the performance of selective sampling techniques. Substantial variance reductions, as well as computational savings, are demonstrated using a sample system with more than 100 elements.
Methods for creating and maintaining keysequence data sets without overwriting the storage medium... more Methods for creating and maintaining keysequence data sets without overwriting the storage medium are described. These methods may be applied to erasable or to write-once storage devices, and they are compatible with conventional device error-management techniques. All past values of data records arepreserved in a data structure called a Write Once B-Tree. Rapid random access is available to records by key value; rapid sequential access is available to records in key-sequence order. Moreover, queries requesting data as of a previous time are processed as rapidly as requests for current data. Access time is proportional to the logarithm of the number of current records in the database. Efficient methods for inserting, updating, and deleting records are described. Upper bounds for tree depth and for storage consumption are given and compared with results from simulation. It is concluded that, with rapidly improving storage technologies, indelible databases will become practical for many applications.
In a two-level computer storage hierarchy, miss ratio measurements are often made from a "cold st... more In a two-level computer storage hierarchy, miss ratio measurements are often made from a "cold start", that is, made with the first-level store initially empty. For large capacities the effect on the measured miss ratio of the misses incurred while filling the first-level store can be significant, even for long reference strings. Use of "warm-start" rather than "cold-start" miss ratios cast doubt on the widespread belief that the observed "S-shape" of lifetime (reciprocal of miss ratio) versus capacity curve indicates a property of behavior of programs that maintain a constant number of pages in main storage. On the other hand, if cold-start miss ratios are measured as a function of capacity and measurement length, then they are useful in studying systems in which operation of a program is periodically interrupted by task switches. It is shown how to obtain, under simple assumptions, the cache miss ratio for multiprogramming from cold-start miss ratio values and how to obtain approximate cold-start miss ratios from warm-start miss ratios.
The design of selective-repeat retransmission protocols to provide reliable transfer of large dat... more The design of selective-repeat retransmission protocols to provide reliable transfer of large data files is discussed. The transmission system is assumed capable of losing, distorting, or reordering the transmitted data frames and acknowledgment frames. The principle design considerations center on methods for managing the finite sequence number space and methods for managing the finite-sized receiver buffer. Under the assumption that there exists a maximum time from transmission of a frame to receipt of an acknowledgment for that frame, methods are described for safe reuse of frame sequence numbers. Previous results by Metzner and Morgan on buffer overflow control are extended to cover non-FIFO transmission systems. A two-dimensional space of design parameters is explored by way of Monte Carlo simulations. For appropriate designs, it is shown that significant increases in throughput over that achieved by the Go-Back4 protocol are possible on high-rate long-delay channels. W 0090-6778/81/0700-0944$00.75 0 1981 IEEE
A retransmission protocol for a broadcast connection (point-to-multipoint) is proposed and its pe... more A retransmission protocol for a broadcast connection (point-to-multipoint) is proposed and its performance characteristics are considered. The protocol is designed for transfers of large files over a satellite channel that is time-shared to carry both the data from the broadcasting transmitter and the set of acknowledgments from the multiple receiver sites. A mathematical model of the transmission system that includes separate error processes for uplink and downlink errors on data transmission, and similar processes for errors on the acknowledgement frames as well, is used to analyze the performance of the scheme. Exact analytical expressions for the relative throughput of the channel are obtained for two special cases: (1) the uplink is error-free; and (2) the acknowledgments are error-free. For the general case, upper and lower bounds are derived and are shown to be virtually indistinguishable for many practical sets of system parameters. The results demonstrate that the broadcasting of large files to multiple receivers can be done both efficiently and reliably.
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