J.R. Haritsa, M.J. Carey, and M. Livny. On Being Optimistic about Real-Time Constraints. In Proceedings of the 9ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, pp.331-343, 1990.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....they are non blocking and deadlock free. Therefore, in recent years, numerous optimistic concurrency control methods have been proposed for real time databases (e.g. 16, 20, 21] Although optimistic approaches have been shown to be better than locking methods for real time database systems [9, 10], they have the problem of unnecessary restarts and heavy restart overhead. This is due to the late conflict detection that increases the restart overhead since some near to complete transactions have to be restarted. Because conflict resolution between the transactions is delayed until a ....

J. R. Haritsa, M. J. Carey, and M. Livny. On being optimistic about real-time constraints. In Proceedings of the 9th ACM Symposium on Principles of Database Systems, pages 331--343, Nashville, Tennessee, 1990. ACM Press.

....framework. Furthermore, by adapting our transactional framework to use information about transaction priorities, the amount of wasted computation due to retries can be reduced, potentially such techniques are likely to result in a significant reduction of missed transaction deadlines [34]. ffl Although wehavedeveloped some simple rules for choosing an object sharing scheme, the right choice of a scheme for implementing an object in an application is entirely 221 dependent on the task set of the application. Further research is required on the issue of determining appropriate ....

J. Haritsa, M. Carey, and M. Livny. On being optimistic about real-time constraints. In Proceedings of the Ninth ACM Symposium on Principles of Database Systems,pages 331--343, 1990.

....prices. These applications also have the need for transaction semantics, hence real time databases are good choices. Most real time database research has evaluated their new ideas via simulation. Also, in much of the past work the only real time issue addressed is that transactions have deadlines [1,2,3,4,5,6,7]. In general, though, transactions that process real time data must use timely and relatively consistent data in order to have correct results. Data read by a transaction must be valid when the transaction completes, which leads to another constraint on completion time, in addition to a ....

J.R. Haritsa, M.J. Carey and M. Livny, "On Being Optimistic about Real-Time Constraints," Proc. of 9 th SIGACT- SIGMOD-SIGART Symposium on Principles of Database Systems, April, 1990.

....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 ....

J. Haritsa, M. Carey, and M. Livny. On being optimistic about real-time constraints. In Systems, 1990.

..... The authors provided the results of simulation experiments examining the performance of the protocol under a wide range of workloads and data access patterns. Some variants of the optimistic concurrency control protocol [40] have also been developed and evaluated for RTDBSs. Haritsa et al. [23] studied the relative performance of lock based and optimistic concurrency techniques in the context of a RTDBS. PA was used as the representative lock based protocol to be compared against the broadcast commit variant of the optimistic protocol. In the broadcast commit protocol, the validation ....

....scheme was found to perform better than the locking scheme only under low data contention. When data contention was high, the situation was reversed due to the overhead of large number of transaction restarts. Those experimental results do not agree with the simulation results of Haritsa et al. [23, 24]. The differences are contributed to the different types of systems involved in evaluations and the different degree of protocol implementation [30] The priority inversion problem that was defined for locking protocols can also exist in a RTDBS that maintains data consistency through use of a ....

J.R. Haritsa, M.J. Carey, M. Livny `On Being Optimistic About Real-Time Constraints', Proceedings of the ACM SIGACT-SIGMOD-SIGART, 1990, pp.331-343.

....protocol combining some existing schemes to capitalize on the advantages of each of those schemes. Haritsa et al. studied, by simulation, the relative performance of two well known classes of concurrency control algorithms (locking protocols and optimistic techniques) in a RTDBS environment [19, 22]. They presented and evaluated a new real time optimistic concurrency control protocol through simulations in [20] Son and Chang [40] investigated methods to apply the priority ceiling protocol as a basis for real time locking protocol in a distributed environment. Agrawal et al. 5] proposed a ....

....is in agreement with our previous results provided above that were obtained by using another parameter (i.e. iat) in varying the level of data contention. On the other hand, it was shown by Haritsa et al. that optimistic protocols are superior to locking protocols at high database access ratios [19, 22]. This result is different from what we obtained in our experiments. However, the experiments of Haritsa et al. were performed in a RTDBS that discards late transactions (i.e. the deadlines are firm) and most of their simulation results were obtained under the assumption that the system has ....

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J.R.Haritsa, M.J.Carey, M.Livny, "On Being Optimistic About Real-Time Constraints", ACM SIGACT-SIGMOD-SIGART, 1990, pp.331-343.

.... may suffer from an unlimited amount of priority inversion time, where priority inversion is a situation in which a higher priority transaction is blocked by a lower priority transaction [28] In the past decade, researchers have proposed various real time concurrency control protocols, e.g. [1, 8, 24, 29, 28, 30, 36], for single site as well as distributed RTDBS. In particular, 8, 28] proposed the idea of priority inheritance, which lets a lower priority transaction inherit the priority of a higher priority transaction which is blocked by the lower priority transaction, to reduce the number of priority ....

....is a situation in which a higher priority transaction is blocked by a lower priority transaction [28] In the past decade, researchers have proposed various real time concurrency control protocols, e.g. 1, 8, 24, 29, 28, 30, 36] for single site as well as distributed RTDBS. In particular, [8, 28] proposed the idea of priority inheritance, which lets a lower priority transaction inherit the priority of a higher priority transaction which is blocked by the lower priority transaction, to reduce the number of priority inversions of the higher priority transaction. The priority inversion ....

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J.R. Haritsa, M. Livny, M.J. Carey. On Being Optimistic about Real-Time Constraints. In Proceedings of the 9 ACM Symposium on Principles of Database Systems, Nashville, pp. 313-343, ACM Press (1990).

.... [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, HSR92, KWL99, SLC91, SRSC91, UB93, UB98]. Some of the potential applications of RTDBS are programmed stock trading systems [AGK95, KR99] air traffic management systems, air navigation systems, and critical patient monitoring systems [KS96] An important performance index of these systems is to handle events and requests in a ....

....strategies, we consider the performance of both soft real time and non real time transactions. The performance of the two well known real time concurrency control protocols, High Priority Two Phase Locking (HP 2PL) AG92] and the optimistic concurrency control protocol with wait 50 (OCC W50) [HCL90, HCL92], are examined in a MSRTDBS. Based on these methods and their performance characteristics, we propose several integrated methods for resolving different types of data conflicts. As a preview, the objectives of the paper are: 1) To study the performance tradeoff of different concurrency control ....

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Haritsa, J.R., Carey, M.J., and Livny, M., On Being Optimistic about Real-Time Constraints, Proceedings of the 9th ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, pp. 331-343, 1990.

.... Hou89, Huan89, Huan91b, Huan91c, Kort90, Kort90b, Kuo92, Lee93, Lee93b, Lee93c, Lee93d, Lin90, Liu88, Marz89, O Nei92, 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 ....

.... 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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Haritsa, J. R., M. J. Carey, and M. Livny, "On Being Optimistic about RealTime Constraints," Proceedings of the 1990 ACM SIGACT-SIGART-SIGMOD Symposium on Principles of Database Systems (PODS), 1990.

....more attention. Different real time optimistic protocols have been proposed. They incorporate different priority conflict resolution methods in the validation phase of a transaction. In this paper we briewly present few popular optimistic protocols and three optimistic protocols in detail. OPT BC [HCL90b] extends classical optimistic protocol with Broadcast Commit [MN82, Rob87] protocol. In Broadcast Commit protocol the transaction notifies other running transactions that conflict with it. The conflicting transactions are restarted. OPT SACRIFICE [HCL90a] is an optimistic protocol which uses a ....

J. R. Haritsa, M. J. Carey, and M. Livny. On being optimistic about real-time constraints. In Proceedings of the 9th ACM Symposium on Principles of Database Systems, pages 331--343. ACM, ACM Press, 1990.

....criterion is timeliness, not average response time or throughput. The scheduling of transactions is driven by priority order. Given these challenges, considerable research has recently been devoted to to designing concurrency control algorithms for RTDBSs and to evaluating their performance [1, 8, 9, 10, 14, 15, 16, 18, 22]. Most of these algorithms are based on one of the two basic concurrency control mechanisms: locking [3] or optimistic concurrency control (OCC) 12] Optimistic concurrency control protocols have the nice properties of being non blocking and deadlock free. These properties make them especially ....

....concurrency control protocol, called OCC DATI. In this paper we concentrate on firm and non real time transaction models. OCC DATI is a fully optimistic protocol and uses forward adjustment. With the new protocol, the number of transaction restarts is smaller than with OCC BC, OPTWAIT, or WAIT 50 [7, 8, 9], because the serialization order of the conflicting transactions is adjusted dynamically. On the other hand, the overhead for supporting dynamic adjust ment is much smaller than the one in OCC DA [15, 16] We also present methods to relax serializability for telecommunication applications. The ....

J. R. Haritsa, M. J. Carey, and M. Livny. On being optimistic about real-time constraints. In Proc. of the 9th ACM Symp. on Principles of Database Systems, pp 331--343. ACM Press, 1990.

....time or throughput. Scheduling of transactions is driven by priority considerations rather than fairness considerations. Given these significant differences, considerable research has been recently devoted to designing concurrency control algorithms for RTDBSs and to evaluating their performance [AGM88, HCL90b, HSTR89, HSRT91, LLH95a, LLH95b, LSH97, LS96, KLR97, MN82]. Most of these algorithms are based on one of the two basic concurrency control mechanisms: locking [EGLT76] or optimistic concurrency control (OCC) KR81] Some of them use priority information in the resolution of conflicts, that is, conflicts are resolved in favor of the higher priority ....

....to reduce the number of transaction restarts and we propose a new optimistic concurrency control protocol, called OCC DATI. OCC DATI is fully optimistic protocol and uses forward adjustment. With the new protocol, the number of transaction restarts is smaller than with OCC BC, OPT WAIT, or WAIT 50 [HCL90b, HCL90a, HSRT91], because the serialization order of the conflicting transactions is adjusted dynamically. On the other hand, the overhead for supporting dynamic adjustment is much smaller than the one in OCC DA [LLH95a, LLH95b] or modified OCC TI [KLR97] Remaining parts of the paper is organized as follows. ....

J. R. Haritsa, M. J. Carey, and M. Livny. On being optimistic about real-time constraints. In Proceedings of the 9th ACM Symposium on Principles of Database Systems, pages 331--343. ACM, ACM Press, 1990.

....to zero. A firm deadline is between these poles; a task loses its value after the deadline but no negative consequence will occur. Given these challenges, considerable research has recently been devoted to to designing concurrency control algorithms for RTDBSs and to evaluating their performance [2, 6 8, 12, 10] Most of these algorithms are based on one of the two basic concurrency control mechanisms: locking [3] or optimistic concurrency control (OCC) 9] In Optimistic Concurrency Control (OCC) 9] transactions are allowed to execute unhindered until they reach their commit point, at which time they ....

J. R. Haritsa, M. J. Carey, and M. Livny. On being optimistic about real-time constraints. In Proceedings of the 9th ACM Symposium on Principles of Database Systems, pages 331--343. ACM, ACM Press, 1990.

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J. Haritsa, M. Carey, and M. Livny, "On Being Optimistic about Real-Time Constraints," Proc. 1990.

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J.R. Haritsa, M.J. Carey, and M. Livny. On Being Optimistic about Real-Time Constraints. In Proceedings of the 9ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, pp.331-343, 1990.

No context found.

J.R. Haritsa, M.J. Carey, and M. Livny, "On Being Optimistic about Real-Time Constraints," Proc. ACM Symp. Principles of Database Systems (PODS), 1990.

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Jayant R. Haritsa, Michael J. Carey, and Miron Linvy. "On being optimistic about real-time constraints." In Prooceedings of the 1990 ACM PODS Symposium, April 1990.

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Jayant R. Haritsa, Michael J. Carey, and Miron Linvy. "On being optimistic about real-time constraints." In Prooceedings of the 1990 ACM PODS Symposium, April 1990.

No context found.

Jayant R. Haritsa, Michael J. Carey, and Miron Linvy. "On being optimistic about real-time constraints." In Prooceedings of the 1990 ACM PODS Symposium, April 1990.

No context found.

Jayant R. Haritsa, Michael J. Carey, and Miron Linvy. "On being optimistic about real-time constraints." In Prooceedings of the 1990 ACM PODS Symposium, April 1990.

No context found.

J.R. Haritsa, M.J. Carey, and M. Livny. On Being Optimistic about Real-Time Constraints. In Proceedings of the 9 ACM SIGACT-SIGMOD-SIGART Symposium on Principles of Database Systems, pp.331-343, 1990.

No context found.

J.R. Haritsa, M.J. Carey, and M. Livny, "On Being Optimistic about Real-Time Constraints," Proc. ACM Symp. Principles of Database Systems (PODS), 1990.

No context found.

J. R. Haritsa, M. J. Carey, and M. Livny. On Being Optimistic about Real-Time Constraints. In ACM Symposium on Principles of Database Systems, 1990.

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Haritsa J.R., Carey M.J., Livny M. `On Being Optimistic About Real-Time Constraints.' ACM SIGACT-SIGMOD-SIGART, 1990, pp.331-343.

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J. R. Haritsa, M. J. Carey, M. Livny `On Being Optimistic About Real-Time Constraints', ACM SIGACT-SIGMOD-SIGART, pp.331-343, 1990.

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