D. Agrawal, A. El Abbadi, and R. Jeffers. Using delayed commitment in locking protocols for real-time databases. In Proc. of ACM SIGMOD Int. Conf. on Management of Data, pages 104--113, 1992.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....transaction inherits a priority of the higher priority transaction. Hybrid Two Phase Locking (HB2PL) 16] adopts the concept of cautious waiting to prevent locking induced trashing and to reduce the impact of priority inversion. Other ideas include Two Phase Locking with Ordered Sharing (2PL OS) [3], Two Phase Locking with Ordered Sharing and Before Images (2PL OS BI) 3] Two Phase Locking with Avoiding Cascaded Aborts (ACA 2PL OS) 3] and Preemptive Two Phase Locking (P2PL) 27] In all these proposals the importance of transactions is the same as the scheduling priority. Priority driven ....

....Two Phase Locking (HB2PL) 16] adopts the concept of cautious waiting to prevent locking induced trashing and to reduce the impact of priority inversion. Other ideas include Two Phase Locking with Ordered Sharing (2PL OS) 3] Two Phase Locking with Ordered Sharing and Before Images (2PL OS BI) [3], Two Phase Locking with Avoiding Cascaded Aborts (ACA 2PL OS) 3] and Preemptive Two Phase Locking (P2PL) 27] In all these proposals the importance of transactions is the same as the scheduling priority. Priority driven concurrency control protocols based on the optimistic approach have not ....

[Article contains additional citation context not shown here]

Agrawal, D., Abbadi, A. E., and Jeffers, R. (1992). Using delayed commitment in locking protocols for real-time databases. In ACM SIGMOD'92.

....used to help another transaction meet its deadline. Expectations about the performance of data priority based locking protocol were confirmed by experimental results [63, 65] Examples of other lock based concurrency control protocols developed for RTDBSs include those provided by Agrawal et al. [5] and by Son et al. 58] The protocols presented in [5] were motivated from the observation that the blocking behavior of locking protocols can greatly degrade the performance of RTDBSs. A new relationship between locks, called ordered sharing, is used in the protocols to eliminate blocking of ....

.... about the performance of data priority based locking protocol were confirmed by experimental results [63, 65] Examples of other lock based concurrency control protocols developed for RTDBSs include those provided by Agrawal et al. 5] and by Son et al. 58] The protocols presented in [5] were motivated from the observation that the blocking behavior of locking protocols can greatly degrade the performance of RTDBSs. A new relationship between locks, called ordered sharing, is used in the protocols to eliminate blocking of read and write operations at the expense of a possible ....

D. Agrawal, A. El Abbadi, R. Jeffers `Using Delayed Commitment in Locking Protocols for Real-Time Databases', Proceedings of the ACM SIGMOD International Conference on the Management of Data, 1992, pp.104-113.

....[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 new locking approach, referred to as ordered sharing, which attempts to eliminate blocking of read and write operations in RTDBSs. In [42] Son et al. examined a priority driven locking protocol which decomposes the problem of concurrency control into two subproblems, namely read write ....

D.Agrawal, A.El Abbadi, R.Jeffers, "Using Delayed Commitment in Locking Protocols for Real-Time Databases", ACM SIGMOD Conference, 1992, pp.104-113.

....to be adversely affected by low priority transactions, a phenomenon known as priority inversion in the real time literature [82] cannot be used in a secure RTDBS. Apart from Wait Promote, other examples of real time CC algorithms that fall into this category include 2PL CR [3] 2PL OS BI [2] and WAIT50 [39] 2.5.4 Resource Service The main physical resources in a database management system are the processors, the memory buffers, and the disks. In a secure RTDBS, service should be provided in a manner that reflects transaction priorities as well as security objectives. One approach ....

....transactions) To generalize the above observation, a real time CC protocol that permits priority inversion [82] to even a limited extent cannot be used in a SRTDBS. Apart from Wait Promote, other examples of real time CC algorithms that fall into this category include WAIT 50 [38] and 2PL OS BI [2]. In the remainder of this section, we present a representative set of CC protocols that by virtue of being free from priority inversion could be used to resolve conflicts in an SRTDBS. These protocols use either locking or optimistic CC [10] as the basic regulatory mechanism. 5.2.1 2PL High ....

D. Agrawal, A. El Abbadi and R. Jeffers, "Using Delayed Commitment in Locking Protocols for Real-Time Databases", Proc. of ACM SIGMOD Conf., June 1992.

.... 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 ....

.... for data consistency other than serializability that can provide a higher level of concurrency by sacrificing data consistency temporarily to some degree [Lin89, Kuo92, Pu92] Considerable work has been devoted to transaction scheduling and concurrency control in real time database systems [Abbo88, Abbo89, Agra92, Buch89, Hari90, Hari90b, Huan89, Huan91b, Huan91c, Lee93, Lee93b, Lee93c, Lee93d, Lin90, Sha88, Son90, Song90, You93]. Most of these studies use the serializability for maintaining data consistency, because there is no general purpose consistency criterion available that is less stringent than serializability, and yet as obviously correct and implementable as serializability. Most of the proposed algorithms for ....

Agrawal, D., A. El Abbadi, and R. Jeffers, "Using Delayed Commitment in Locking Protocols for Real-Time Databases," Proceedings of the ACM SIGMOD International Conference on Management of Data, June 1992.

....priority transaction inherits higher priority transactions priority. Hybrid Two Phase Locking (HB2PL) 15] adopts the concept of cautious waiting to prevent locking induced trashing and to reduce the impact of priority inversion. Other ideas include Two Phase Locking with Ordered Sharing (2PL OS) [2], Two Phase Locking with Ordered Sharing and Before Images (2PL OS BI) 2] Two Phase Locking with Avoiding Cascaded Aborts (ACA 2PL OS) 2] and Preemptive Two Phase Locking (P2PL) 27] An alternative for concurrency control in RTDBS is to use real time Static 2PL (RT S2PL) 23] In S2PL, the ....

....Two Phase Locking (HB2PL) 15] adopts the concept of cautious waiting to prevent locking induced trashing and to reduce the impact of priority inversion. Other ideas include Two Phase Locking with Ordered Sharing (2PL OS) 2] Two Phase Locking with Ordered Sharing and Before Images (2PL OS BI) [2], Two Phase Locking with Avoiding Cascaded Aborts (ACA 2PL OS) 2] and Preemptive Two Phase Locking (P2PL) 27] An alternative for concurrency control in RTDBS is to use real time Static 2PL (RT S2PL) 23] In S2PL, the required locks of transaction are assumed to be known before its execution. ....

[Article contains additional citation context not shown here]

D. Agrawal, A. E. Abbadi, and R. Jeffers. Using delayed commitment in locking protocols for real-time databases. In ACM SIGMOD'92, 1992.

....submits a transaction with a tight deadline in an SRTDBS. In this case, priority assignment becomes difficult since assigning a high priority may cause a security violation whereas assigning a low priority may result in a missed deadline. 2. Although a variety of real time CC protocols (e.g. [1, 4, 19, 27]) have been proposed during the last decade, not all of them may be amenable to supporting the non interference requirement. 3. Apart from the noise approach mentioned earlier, covert channels can also be eliminated by static resource allocation policies, wherein each transaction security class ....

....to be adversely affected by low priority transactions, a phenomenon known as priority inversion in the real time literature [31] cannot be used in a secure RTDBS. Apart from Wait Promote, other examples of real time CC algorithms that fall into this category include 2PL CR [1] 2PL OS BI [4] and WAIT 50 [19] 4. Secure CC Protocols In this section, we describe the CC protocols that are evaluated in our study. These include two well known real time protocols: 2PL HP [1] which is based on locking, and OPT WAIT [19] which is based on optimistic concurrency control. Both these ....

D. Agrawal, A. El Abbadi and R. Jeffers, "Using Delayed Commitment in Locking Protocols for Real-Time Databases", Proc. of ACM SIGMOD Conf., June 1992.

....before their deadlines expire. Research on real time database systems has focused mainly on identifying the appropriate choice, with respect to meeting the real time goals, for the various database system policies such as priority assignment, concurrency control, memory management, etc. e.g. [AG92, HCL92, AEJ92, PCL94, HJC93]) However, the design and evaluation of concurrency control algorithms for indexes, which are an integral part of database systems, has not yet been considered for the real time environment (to the best of our knowledge) While index concurrency control is an important issue in a conventional ....

D. Agrawal, A. El Abbadi and R. Jeffers. Using Delayed Commitment in Locking Protocols for Real-Time Databases. In Proc. of ACM SIGMOD Conference, June 1992.

....overhead . These difficulties will increase in importance as technology moves more and more towards concurrent and distributed systems. It is therefore important to develop new ways to increase concurrency in such systems. Several researchers have considered alternatives ( Gar83] MRBKS92] [AAJ92], LKS91] The main idea is to identify substeps within each transaction that need to be executed atomically. The breakpoints between substeps are points at which concurrency can be considered. However, these techniques place a severe burden on database users to identify steps and breakpoints. ....

D. Agrawal, A. El Abbadi, R. Jeffers "Using Delayed Commitment in Lock ing Protocols for Real-time Databases"; Proceeding of the 1992 ACM SIGMOD; San Diego, California June 2-5 Page: 104-113; 1992.

....to be adversely a ected by low priority transactions, a phenomenon known as priority 6 inversion in the real time literature [26] cannot be used in a secure RTDBS. Apart from Wait Promote, other examples of real time CC algorithms that fall into this category include 2PL CR [1] 2PL OS BI [3] and WAIT 50 [18] 3.3 RESOURCE ALLOCATION Apart from the noise approach mentioned earlier, covert channels can also be eliminated by static resource allocation policies, wherein each transaction security class has a set of pre assigned resources. This approach is taken, for example, in ....

D. Agrawal, A. El Abbadi and R. Jeers, \Using Delayed Commitment in Locking Protocols for Real-Time Databases", Proc. of ACM SIGMOD Conf., June 1992.

....requests. Our work is in a more general 3 database context, where such restrictions on order may not be acceptable. Instead, we use intention locks. We make use of deferred updates in maintaining our lock graph. While no one has proposed the use of deferred updates for locking hierarchies, see [1, 24, 21] for some recent papers that use deferred updates for other purposes. 3 MOTIVATION Multi granularity locking is used to resolve the tradeoff between concurrency and overhead concurrency is increased if fine locking granules (e.g. records or fields) are used, but fine locking granules are very ....

D. Agrawal, A. El Abbadi, and R. Jeffers. Using delayed commitment in locking protocols for real-time databases. In Proc. SIGMOD, pages 104--113, June 1992.

....especially important since new flavors of both real time and conventional concurrency control protocols are constantly being proposed in 1 If a CCM is chosen by more than one transaction class, then these classes are merged into a single class from the CCM s perspective. the literature (e.g. [AE90, AEJ92, BB94, LS93]) and RTDBS users may wish to take advantage of these new algorithms. Note also that this open feature of our architecture makes the integration scheme applicable in not just the real time database context but in any environment where there are multiple transaction classes with different ....

D. Agrawal, A. El Abbadi and R. Jeffers. Using Delayed Commitment in Locking Protocols for Real-Time Databases. In Proc. of ACM SIGMOD Conference, June 1992.

.... classes of concurrency control algorithms (locking protocols and optimistic techniques) in a RTDBS environment [Haritsa et al. 1990, 1992] Agrawal et al. proposed a new locking approach, referred to as ordered sharing, which attempts to eliminate blocking of read and write operations in RTDBSs [Agrawal et al. 1992]. Son et al. examined a priority driven locking protocol which decomposes the problem of concurrency control into two subproblems, namely read write synchronization and write write synchronization, and integrates the solutions to two subproblems considering transaction priorities [Son et al. 1992] ....

D. Agrawal, A. El Abbadi, R. Jeffers, Using Delayed Commitment in Locking Protocols for Real-Time Databases, ACM SIGMOD Conference, 104-113.

....of lesser worth. Figure 10 shows the increased value added to the system that results from delaying the commitment of T 1 , thus allowing T o 2 to commit before its deadline and contribute a higher value to the system. Our approach for introducing delays is similar to those proposed in [AAJ92, HCL90a, SPL92]. Whenever a shadow T o u finishes its execution, we evaluate if it is advantageous to defer T o u s commitment. Finding the best point in time to commit a finished shadow T o u is a very hard optimization problem, since it requires the consideration of all possible serialization orders of ....

D. Agrawal, A. El Abbadi, and R. Jeffers. Using delayed commitment in locking protocols for realtime databases. In Proceedings of the 1992 ACM SIGMOD International Conference on Management of Data, San Diego, Ca, 1992.

....the performance of the transaction scheduling algorithms. Concurrency Control Techniques with Serializability: Concurrency control techniques for real time databases that use serializability as the correctness criteria include lock based protocols such as two phase locking and its variants [3, 1, 7, 60, 86, 88, 179, 180, 193, 214, 216], optimistic concurrency control protocols [74, 78, 88, 121] and timestamp ordering protocols [133, 195, 215] Using any of these techniques, conflicts between two real time transactions or between one real time transaction and a set of real time transactions are detected. For lock based ....

....is aborted. Otherwise, the lock requesting transaction is blocked. The performance of both priority inheritance and priority abort as well as their variations have been compared in several studies [1, 3, 77, 89, 215] Other lock based protocols for real time databases include ordered sharing [5, 6, 7] that eliminates blocking, and dynamic adjustment of the serialization order [133] of transactions in order to execute high priority transactions before low priority transactions. Timestamp ordering protocols [194, 215, 216] use timestamps that are assigned to transactions when they are started, ....

Agrawal D., Abbadi, A. E., and Jeffers, R., "Using Delayed Commitment in Locking Protocols for Real-Time Databases," in Proceedings of the ACM International Conference on Management of Data, pp. 104--113, 1992.

....to be adversely affected by low priority transactions, a phenomenon known as priority inversion in the real time literature [18] cannot be used in a secure RTDBS. Apart from Wait Promote, other examples of real time CC algorithms that fall into this category include 2PL CR [3] 2PL OS BI [2] and WAIT 50 [9] In the remainder of this section, we briefly present a representative set of concurrency control protocols that, by virtue of being completely free from priority inversion, could be used to resolve conflicts in a secure real time database system. These protocols use either ....

D. Agrawal, A. El Abbadi and R. Jeffers, "Using Delayed Commitment in Locking Protocols for Real-Time Databases", Proc. of ACM SIGMOD Conf., June 1992.

.... with PCC based techniques to make it possible for more urgent transactions to abort conflicting, less urgent ones (thus avoiding the hazards of blockages) Examples include the Priority Abort (PA) technique [3] Priority Inheritance (PI) technique [56] and variations of these techniques [55, 32, 7, 58, 64]. These priorities are also used in conjunction with OCC based techniques to favor more urgent transactions when conflicting, less urgent ones attempt to validate and commit (thus avoiding the hazards of restarts) Examples include the Broadcast Commit (BC) technique [40, 27] and the Wait 50 ....

D. Agrawal, A. El Abbadi, and R. Jeffers. Using delayed commitment in locking protocols for real-time databases. In Proceedings of the 1992 ACM SIGMOD International Conference on Management of Data, San Diego, Ca, 1992.

....constraints of transactions. The results of the substantial amount of research devoted to the development and performance evaluation of concurrency control protocols have appeared in the following papers: Abbott GarciaMolina 1988] Abbott Garcia Molina 1989] Abbott Garcia Molina 1992] [Agrawal et al. 1992], Bestavros 1993] Bestavros and Braoudakis 1994] Biyabani et al. 1988] Buchmann et al. 1989] Chakravarthy et al. 1994a] Chakravarthy et al. 1994b] Chen Lin 1990] David et al. 1994] DiPippo Wolfe 1993] Goyal et al. 1995] Haritsa et al. 1990a] Haritsa et al. 1990b] ....

D. Agrawal, A. El Abbadi, R. Jeffers `Using Delayed Commitment in Locking Protocols for Real-Time Databases', Proceedings of the ACM SIGMOD International Conference on the Management of Data, 1992, pp.104-113.

....T 2 V C Rx V C Blocked 0 0 1 Value D 1 A 1 D 2 A 2 t 1 t 2 v 1 v 2 a 1 a 2 o o (a) Time T 2 S Rx Time T 1 S Wx A T 2 V C Blocked 0 0 1 Value D 1 A 1 D 2 A 2 1 2 v 1 v 2 a 1 a 2 Delayed C o o F (b) Figure 10: Value added to the system (a) without deferment (b) with deferment. to those proposed in [Agra92, Hari90a, Son92]. Whenever a transaction shadow T o u (executing on behalf of transaction Tu ) finishes its execution, we evaluate if it is advantageous to defer T o u s commitment for a later point in time. Finding the best point in time to commit a finished shadow T o u is a very hard optimization problem, ....

D. Agrawal, A. El Abbadi, and R. Jeffers. "Using delayed commitment in locking protocols for realtime databases." In Proceedings of the 1992 ACM SIGMOD International Conference on Management of Data, San Diego, Ca, 1992.

No context found.

D. Agrawal, A. El Abbadi, and R. Jeffers. Using delayed commitment in locking protocols for real-time databases. In Proc. of ACM SIGMOD Int. Conf. on Management of Data, pages 104--113, 1992.

No context found.

D. Agrawal, A. El Abbadi, and R. Jeffers. Using delayed commitment in locking protocols for real-time databases. In Proceedings of the 1992.

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