R. K. Abbott and H. Garcia-Molina. Scheduling realtime transactions with disk resident data. In Proceedings of Very Large Database Conference, pages 385-- 396, 1989.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....efficient garbage collection distinguish our work. Our work on making read only transactions completely non blocking and their execution times more predictable is complementary to the time cognizant transaction processing schemes proposed in the real time database systems literature [SZ88, AGM88, AGM89, HCL90b, HCL90a, HSRT89, HSRT91, HCL93, Ram93] Our use of main memory technology and version based concurrency control schemes enable transaction running times to be estimated more accurately. Consequently, scheduling algorithms can generate better schedules, that is, schedules in which more ....

R. Abbott and H. Garcia-Molina. Scheduling real-time transactions with disk-resident data. In Procs. of the International Conf. on Very Large Databases, 1989.

....contract number E30602 97 2 0287 and in part under contract number F30602 96 1 0160. Mr. Molano was funded by a research grant from the Community of Madrid and by the National R D Program of Spain under contracts TIC96 0982 and TIC97 0438. one type (namely network packets) Work described in [1, 2, 7, 8] study various aspects of real time disks and filesystems. The approach used in [1] is a variation of the Scan algorithm in which the SCAN direction changes towards the Earliest Deadline First request only if the deadline is considered to be met. At any scheduling point the request with the ....

....Molano was funded by a research grant from the Community of Madrid and by the National R D Program of Spain under contracts TIC96 0982 and TIC97 0438. one type (namely network packets) Work described in [1, 2, 7, 8] study various aspects of real time disks and filesystems. The approach used in [1] is a variation of the Scan algorithm in which the SCAN direction changes towards the Earliest Deadline First request only if the deadline is considered to be met. At any scheduling point the request with the Earliest Feasible deadline is chosen for service and the disk head scans towards it. Chen ....

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R. Abbott and H. Garcia-Molina. Scheduling Real-Time Transactions with Disk Resident Data X Server. Tech. Rept. CS-TR-207-89, Department of Computer Science, Princeton University, Feb., 1989.

....In this algorithm, the request with the earliest feasible deadline is chosen as the target and determines the scanning direction. A deadline is feasible if it is estimated that it can be met. If there is no request with a feasible deadline, then simply the closest request is serviced. In [2], Abbott and Garcia Molina studied an IO architecture that handles read requests and write requests differently. The architecture assumes that write operations of a transaction are always performed after the transaction has committed. While a read request is assigned a priority based on the timing ....

....(Priority Hints) was shown to perform as well as Priority DBMIN and better than Priority LRU. Abbott and Garcia Molina [3] presented and evaluated two new buffer management techniques to be used in scheduling IO requests with deadlines. On the basis of the IO architecture they provided in [2] (as discussed in the preceding section) read and write requests are treated separately by the proposed techniques. Read requests are assumed to be issued by uncommitted transactions and receive service in accordance with the timing constraints of the transactions that issued them. Write ....

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R. Abbott, H. Garcia-Molina `Scheduling Real-Time Transactions with Disk Resident Data', Proceedings of the 15th International Conference on Very Large Data Bases, 1989, pp.385-396.

....access requests of transactions. An extensive exploration of the issues in RTDBSs is provided in [32] The transaction scheduling problem in RTDBSs has been addressed by a number of recent studies. The first attempt to evaluate the performance of scheduling algorithms in RTDBSs was provided in [1, 2]. Abbott and Garcia Molina described and evaluated through simulation a group of real time scheduling policies based on enforcing data consistency by using a two phase locking concurrency control mechanism. An extended version of their work appeared recently in [4] In [3] they provided a study ....

....tr length (i.e. the number of data items accessed by each transaction) The mean interarrival time value (iat) was fixed at 400 msec and the same value was assumed for the maximum transaction population (i.e. 50) with each tr length value considered. The range of tr length values employed was [2,10], which corresponds to a database access ratio of 0.05 to 0.25. The results are displayed in Figure 6 for protocols PI and OPT. The reaction of protocols PB and CP to the change in the database access ratio was similar to that of protocol PI, thus, PI was selected as representative for the locking ....

R.Abbott, H.Garcia-Molina, "Scheduling Real-Time Transactions with Disk Resident Data", 15th International Conference on Very Large Data Bases, 1989, pp.385-396.

....usually are considered to be trade secrets. This section will discuss a few success stories. 4. 1 Disks Disk Scheduling Numerous studies have investigated the performance of disk I O scheduling algorithms involving command queuing (e.g. 18, 51, 52, 63, 64, 65] real time applications (e.g. [66, 67, 68, 69]) and database applications (e.g. 70] Event driven simulation studies of disk scheduling algorithms that use rotational position information appear in [52] these studies were used by Hewlett Packard s Disk Memory Division in the design of products. Disk Cache Performance evaluation methods ....

R. Abbott and H. Garcia-Molina, \Scheduling real-time transactions with disk resident data," in Proceedings of 15th International Conference on Very Large Data Bases, (Amsterdam, The Netherlands), pp. 385-396, Aug. 1989.

....immediately the transaction should wait until it will become possible. Most of pessimistic algorithms are based on locks. The classical pessimistic algorithm is the widely used two phase locking (2PL) 5] Real time systems usually use modified versions of 2PL, such as 2PL HP, 2PL WP, 2PL PC [1, 2, 13]. These protocol modifications take into consideration real time aspects, such as transaction priorities. According to 2PL HP, conflict situations are resolved in favor of the transaction with higher priority. When a transaction requests a lock on an object held by an other transaction in a ....

R. Abbott and H. Garcia-Molina. Scheduling real-time transactions with disk resident data. In Procedings of the 15th VLDB Conference, August 1989.

....in a real time database system are usually associated with deadlines. Any deadline violation of a hard real time transaction may result in a catastrophe, while deadline violations of soft real time transactions might only cause a degraded level of system performance without a total system failure [AG89, HCL92, ORP96, YWLS92]. In the past two decades, researchers have proposed various efficient real time concurrency control techniques to either reduce the number of deadline violations for soft (and firm 1 ) real time transactions or guarantee the deadlines of hard real time transactions [AG92, BN96, HCL90, HS99, ....

....These factors are detrimental to satisfying the transaction deadlines [CSKT91] On the other hand, the probability of cache hit can significantly affect the impact of the disk scheduling on the performance of the protocols. If a deadline cognizant technique is adopted to schedule disk requests [AG89], requests from transactions with earlier deadlines may have a higher chance of being served first. The disk thus acts (indirectly) as an agent that controls the progress of the transactions, and the waiting time of non real time transactions will be much longer than that of the soft real time ....

Abbott, R. and H. Garcia-Molina, "Scheduling Real-time Transactions with Disk Resident Data", in Proceedings of the 15 th VLDB Conference, pp. 356-396, 1989.

.... Pu92, Rajk89, Sha88, Son90, Son92, Song90, Stan88, Vrbs88] The subjects addressed in these papers include the modeling of real time transactions and real time database systems [Abbo88, Buch89, Care89, Daya88, Hari90, Huan89, Kort90, Liu88, Sha88, Stan88] scheduling of real time transactions [Abbo88, Abbo89, Huan89, Stan88, Sha88], concurrency control and data conflict resolution [Abbo88, Abbo89, Agra92, Buch89, Hari90, Hari90b, Huan89, Huan91b, Huan91c, Lee93, Lee93b, Lee93c, Lee93d, Lin90, Sha88, Son90, Son90b, Song90, You93] processing of queries with real time constraints [Hou89] buffer management [Care89, Huan90] ....

.... these papers include the modeling of real time transactions and real time database systems [Abbo88, Buch89, Care89, Daya88, Hari90, Huan89, Kort90, Liu88, Sha88, Stan88] scheduling of real time transactions [Abbo88, Abbo89, Huan89, Stan88, Sha88] concurrency control and data conflict resolution [Abbo88, Abbo89, Agra92, Buch89, Hari90, Hari90b, Huan89, Huan91b, Huan91c, Lee93, Lee93b, Lee93c, Lee93d, Lin90, Sha88, Son90, Son90b, Song90, You93], processing of queries with real time constraints [Hou89] buffer management [Care89, Huan90] and I O scheduling [Abbo90, Care89, Chen91] A number of papers on related issues have also appeared. These include work on a protocol for timed atomic commitment [Davi91] fast recovery protocols for ....

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Abbott, R. and H. Garcia-Molina, "Scheduling Real-Time Transactions with Disk Resident Data," Proceedings of the 15th VLDB Conference, August 1989.

....of ECA rules. In particular a lot of work has been done on semantics of event and rule specification and evaluation, as well as coupling modes between conditions and actions. None of this work considers a real time context. The pioneering work in RTDBS performance evaluation was reported in [1, 2, 3], where the authors simulated a number of CC protocols based on the two phase locking algorithm. However, this work was not examined in an active context. A subset of notable RTDBS work [23, 22, 25, 29, 44, 5, 14] Again, all this work has been performed without considering the effects of ....

R. Abbott and H. Garcia-Molina. Scheduling real-time transactions with disk resident data. In Proceedings of the 15th VLDB, 1989.

....protocols designed for a single type of transactions. For example, the well known priority ceiling protocol (PCP) Sha et al. 1990; Sha et al. 1991) designed for HRT) requires a static system that is usually not true for a system with SRT. The Higher Priority Two Phase Locking Protocol (HP 2PL) (Abbott and Garcia Molina, 1989; Abbott and Garcia Molina, 1992) which is designed for SRT, cannot guarantee the deadlines of HRT or even be suitable to a RTDBS that consists of mixed SRT and non real time transactions (NRT) The response times of NRT may be greatly affected because of the restart policy of HP 2PL. A NRT may ....

....results are provided in Section 5. Section 6 is the conclusion. 2 Real time Concurrency Control Protocols 2. 1 Real time Concurrency Control Protocols for Single Type of Transactions Real time concurrency control protocols are often extended from traditional concurrency control protocols (Abbott and Garcia Molina, 1989; Abbott and Garcia Molina, 1992; Haritsa et al. 1990; Haritsa et al. 1992; Huang et al. 1992; Sha et al. 1990; Sha et al. 1991; Ulusoy and Buchmann, 1998) Most lock based real time concurrency control protocols follow from the two phase locking scheme (2PL) Bernstein et al. 1987) For ....

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Abbott, R. and H. Garcia-Molina. 1989. Scheduling Real-time Transactions with Disk Resident Data. In: Proceedings of the 15th VLDB Conference, pp. 356-396.

....may cause aborts or delays of indeterminate length. There has been extensive study of real time systems [Sta88] Formal aspects of such systems have been examined from the standpoints of scheduling (e.g. HMR 89] and verification [JM86] In the context of real time databases, AGM88, AGM89] consider alternative queuing disciplines with lock based concurrency control of real time transactions, and use simulation results to compare 2 these techniques. The research in [SRL88] proposes concurrency control techniques for distributed real time systems based on a partitioning of data, ....

R. Abbott and H. Garcia-Molina. Scheduling real time transactions with disk resident data. In Proceedings of the Fifteenth International Conference on Very Large Databases, Amsterdam, pages 385--396, 1989.

.... systems; Database management; Architecture; Intelligent memory 1 Introduction Applications that require real time functionality are difficult to implement using standard hardware and software systems [Sta88] This is also the case with a real time database (RTDB) management system [AGM88, AGM89, BMHD89, C 89, DLW90, HCL90, KSS90, Sin88, Son88, SZ88] which straddles the areas of a high performance database management system (DBMS) and a real time system (RTS) A general RTDB application may be regarded as a reactive process control system [Sin88] The world external to the computer ....

R. Abbott and H. Garcia-Molina. Scheduling real time transactions with disk resident data. In Proceedings of the Fifteenth International Conference on Very Large Databases, Amsterdam, pages 385--396, 1989.

....from the norm in that we do not directly address the question of time constrained scheduling at each local site. Instead, we consider issues pertinent to the distributed environment where the local scheduling is handled through the use of methods that have been previously explored [AGM88, AGM89, BMHD89, C 89, HCL90b, HCL90a, KSS90] Thus, a transaction that accesses data at several sites, does so by the use of a subtransaction at each concerned site, and each such subtransaction is subject to the local concurrency control mechanism at its particular site. We adopt such an approach ....

....trends and makes decisions regarding the sale or buying of options, and sends these to the sites to effect the transactions. The need for a coordinated set of actions at the different sites is evident. Also, the need for fast, real time responses is necessary to exploit the trends in the market [AGM89] We assume that there is a need to transfer money from one site to another, or to audit the total amount of money that exists in accounts managed at more than one site. Such systems are usually designed using a transaction processing paradigm. Consider a global transaction T 1 that transfers ....

R. Abbott and H. Garcia-Molina. Scheduling real time transactions with disk resident data. In Proceedings of the Fifteenth International Conference on Very Large Databases, Amsterdam, pages 385--396, 1989.

....transaction wakeup, deadlock, buffer management, and disk I O scheduling [21, 23, 25, 26, 50, 100] Each of these algorithms or protocols should directly address the real time constraints. To date, work on real time databases has investigated a centralized, secondary storage real time database [1, 2, 3]. As is usually required in traditional database systems, work so far has required that all the real time transaction operations maintain data consistency as defined by serializability. Serializability may be relaxed in some real time database systems, depending on the application environment and ....

R. Abbott and H. Garcia-Molina, "Scheduling Real-Time Transactions with Disk Resident Data," Proceedings of the 15th VLDB Conference, 1989.

....0.1, is used to determine whether a disk access is required. CPU scheduling is an important issue when dealing with real time transaction systems. We chose the following algorithm. ffl CPU Scheduling The earliest deadline (ED) algorithm is used for CPU scheduling. As mentioned in the literature [2], a major drawback of this algorithm is that it may assign the highest priority to a transaction that has already missed or is about to miss its deadline. To partially overcome this weakness, we propose a modified ED algorithm which, instead of scheduling according to a transaction s deadline, ....

Abbott, R. and Garcia-Molina, H., "Scheduling Real-Time Transactions with Disk Resident Data," A Technical Report, CS-TR-207-89, Princeton University, Feb. 1989.

....is known to be NP complete (see [17] and [36] Comprehensive surveys on real time databases can be found in [2] and [33] Our scheduling approach will follow some of the ideas of [2] especially using soft real time. Special scheduling algorithms for real time databases are e.g. detailed in [1], where earliest deadline, least slack and high priority strategies are studied. Another approach considers static and dynamic costs associated with tasks and transactions, see [23] Our approach uses domain specific knowledge about tasks and agents, particularly human users, for heuristic ....

R. Abbott and H. Garcia-Molina. Scheduling real--time transactions with disk--resident data. In Proc. Intl. Conf. on Very Large Data Bases, pages 385--396, Amsterdam, Netherland, 1989.

....time critical scheduling methods to observe the timing requirements of transactions [30] A considerable amount of RTDBS research has been devoted to performance evaluation of time cognizant concurrency control protocols. However, the performance studies were either based on simulation (e.g. [1, 2, 3, 10, 11, 20, 23, 27, 28, 29]) or carried out on a RTDBS testbed (e.g. 14, 15] To the best of our knowledge, no analytic performance study has been reported so far involving the evaluation of concurrency control protocols in RTDBSs, which is the main contribution of this paper. 1 The behavior of concurrency control ....

R. Abbott, H. Garcia-Molina `Scheduling Real-Time Transactions with Disk Resident Data', 15th International Conference on Very Large Data Bases, pp.385-396, 1989.

No context found.

R. K. Abbott and H. Garcia-Molina. Scheduling realtime transactions with disk resident data. In Proceedings of Very Large Database Conference, pages 385-- 396, 1989.

No context found.

R. K. Abbott and H. Garcia-Molina. Scheduling realtime transactions with disk resident data. In Proceedings of Very Large Database Conference, pages 385-- 396, 1989.

No context found.

R. Abbott and H. Garcia-Molina. Scheduling Real-Time Transactions with Disk Resident Data. In Very Large Data Bases, 1989.

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Abbott R., Garcia-Molina H. `Scheduling Real-Time Transactions with Disk Resident Data.' Proc. 15th Int. Conf. on Very Large Data Bases, 1989, pp.385-396.

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R. Abbott and H. Garcia-Molina. Scheduling real-time transactions with disk resident data. In Proceedings 15th International Conference on Very Large Data Bases, Los Angeles, 1989.

No context found.

R. Abbott, H. Garcia-Molina `Scheduling Real-Time Transactions with Disk Resident Data', 15th International Conference on Very Large Data Bases, pp.385-396, 1989.

No context found.

Abbott, R. and H. Garcia-Molina. (1989). "Scheduling Real-Time Transactions with Disk Resident Data." In Proc. of Conf. on Very Large Databases.

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Abbott, R. and Garcia-Molina, H. Scheduling Real-Time Transactions with Disk Resident Data. Science, Princeton, NJ, 1989.

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