Lee, J. and Son, S.H. (1995) Concurrency Control Algorithms for Real-Time Database Systems, in Performance of Concurrency Control Mechanisms in Centralized Database Systems (ed. Vijay Kumar), Prentice Hall, 429-60.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....the executing committing conflict an important problem for the performance of a DRTDBS. However, to our best knowledge, the executing committing conflict problem has not received adequate attention in the past. Proposals started to appear in the literature only recently. Although several RT CCPs [5, 7, 13, 14, 15, 16] have been proposed, they are mainly for solving the executing executing conflicts. The previous studies are [1, 2, 17, 18] In [17] and [18] compensation approaches are suggested in which the participants of a transaction are allowed to commit unilaterally, with an attempt to reduce the ....

....will be allowed to borrow the value from the committing transaction. In [2] it was found that the best range for the healthy factor is between 1 to 2 and its performance with this range is similar. 5.1.1. Transaction deadline assignment Following the assumptions described in previous works [5, 6, 8, 12, 13, 15, 20, 24], the transaction deadlines are assumed to be proportional to their expected execution 684 K. Y. LAM et al. and are defined as follows: Deadline T ar (T stage1 T stage2 ) slack factor. The slack factor (SF) is a random variable uniformly distributed between two bounds. T ar is the ....

Lee, J. (1994) Concurrency control algorithms for real-time database systems. PhD Thesis, Department of Computer Science, University of Virginia.

....and non real time transactions under different real time supports in the system. Keywords: mixed real time database systems, concurrency control protocols, transaction scheduling 2 1 Introduction Research in real time database systems (RTDBS) has received a lot of interests in the past decade [AG92, B96, BLS87, DSK00, HR00, KWL99, L94, OS95, SKS96, YWLS92]. Transactions 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 ....

....OCC W50 gives the best performance. 10 4.1. 2 Mixed OCC Wait 50 Protocol (MOCC W50) Past research suggests that optimistic approaches are better than lock based protocols in concurrency control for soft (and firm) real time transactions when it is combined with the forward validation scheme [HCL92, L94]. To apply an optimistic protocol (such as OCC W50) to a MSRTDBS, the simplest way is to assign the same priority to non real time transactions and assign higher priorities to soft real time transactions. Note that different variants of priority cognitive optimistic concurrency control methods ....

Lee, J., Concurrency Control Algorithms for Real-time Database Systems, Ph.D. Thesis, Department of Computer Science, University of Virginia, 1994.

.... may occurs [Rajk91] which is highly undesirable to real time scheduling as it can greatly degrade the schedulability of the adopted CPU scheduling algorithm and affect the system performance [Liu73, Stan95] In recent years, different real time concurrency control protocols have been proposed [Agra95, Best95, Hari92, Huan92, Lam95, Lee94, Ulus94]. Most of them are based on 2PL owing to its popularity and simplicity in implementation [Eswa76] The correctness notion adopted in these protocols is serializability [Bern87] For example, in High Priority Two Phase Locking (H2PL) if the requesting lock is being held by a lower priority ....

....traditional database systems is on the deadlines of the transactions. Based on this assumption, different real time concurrency control protocols have been proposed by modifying the concurrency control protocols for traditional database systems such as 2PL [Abbo92, Huan92] and optimistic method [Hari92, Lee94]. Their objectives are to minimise the number deadline missing transactions and maintain database consistency. They resolve the problem of priority inversion [Rajk91] by blocking or restarting transactions. They use serializability as the notion of correctness as it is commonly accepted as the ....

J. Lee, "Concurrency Control Algorithms for Real-time Database Systems", Ph.D. Thesis, Department of Computer Science, University of Virginia, 1994.

....50 wait; for 8 T a 2 conf lict set(T v ) restart(T a ) commit WS(T v ) to database; g Figure 3: Validation algorithm for WAIT 50. Performance studies in [HCL90a] has shown WAIT 50 to provide significant performance gains over OPT BC, OPT SACRIFICE and OPT WAIT. 7 3. 2 OCC TI OCC TI [LS93, Lee94] protocol resolves conflicts using time intervals of the transactions. Every transaction must be executed in a specific time slot. When an access conflict occurs, it is resolved using the read and write sets of the transaction together with the allocated time slot. Time slots are adjusted when a ....

J. Lee. Concurrency Control Algorithms for Real-Time Database Systems. PhD thesis, Faculty of the School of Engineering and Applied Science, University of Virginia, January 1994.

....timestamp of committed transactions that have read or written, respectively, the data object D i . Let TS(T v ) be the final timestamp of the validating transaction T v and T I(T i ) timestamp interval of the transaction T i . Let imp(T i ) be the importance of transaction T i . The OCC TI [14, 13] protocol resolves conflicts using time intervals of the transactions. Every transaction must be executed within a specific time slot. When an access conflict occurs, it is resolved using the read and write sets of the transaction together with the allocated time slot. Time slots are adjusted when ....

J. Lee. Concurrency Control Algorithms for Real-Time Database Systems. PhD thesis, Faculty of the School of Engineering and Applied Science, University of Virginia, January 1994.

....transactions that conflict with it have higher priorities. 24 Otherwise it commits and all the conflicting transactions are restarted. Performance studies in [HCL90a] have shown WAIT 50 to provide significant performance gains over OPT BC, OPT SACRIFICE and OPT WAIT. 5. 1 OCC TI The OCC TI [LS93, Lee94] protocol resolves conflicts using time intervals of the transactions. Every transaction must be executed within a specific time slot. When an access conflict occurs, it is resolved using the read and write sets of the transaction together with the allocated time slot. Time slots are adjusted ....

....T j s write (forward ordering) At the beginning of the validation (figure 10) the final timestamp of the validated transaction is determined from the timestamp interval allocated to the transaction. In this algorithm, the minimum value of T I(T v ) is selected as the timestamp TS(T v ) LS93, Lee94] The timestamp intervals of all concurrently running and conflicting transactions must be adjusted so as to reflect the serialization order. Any transaction whose timestamp interval becomes empty must be restarted. The adjustment of timestamp intervals of a running transaction iterates through ....

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J. Lee. Concurrency Control Algorithms for Real-Time Database Systems. PhD thesis, Faculty of the School of Engineering and Applied Science, University of Virginia, January 1994.

....executing committing conflict an important problem to the performance of a DRTDBS. However, to our best knowledge, the executing committing conflict problem has not been receiving adequate attention in the past. Proposals started to appear in the literatures only recently. Although several RT CCPs [5, 7, 13, 14, 15, 16] have been proposed, they are mainly for solving the executing executing conflicts. The previous studies are [1, 2, 17, 18] In [17] and [18] compensation approaches are suggested in which the participants of a transaction are allowed to commit unilaterally with an attempt to reduce the ....

....borrow the value from the committing transaction. In [2] it had found that the best range for the healthy factor is between 1 to 2 and its performance with this range is similar. 5.1. 1 Transaction Deadline Assignment Local Database 22 Following the assumptions described in the previous work [5, 6, 8, 12, 13, 15, 20, 24], the transaction deadlines are assumed to be proportional to their expected execution time 1 and are defined as follows: Deadline = T ar (T stage1 T stage2 ) slack factor The slack factor (SF) is a random variable uniformly distributed between two bounds. T ar is the arrival time of ....

Lee, J. (1994) Concurrency Control Algorithms for Real-time Database Systems. Ph.D. Thesis, Department of Computer Science, University of Virginia.

....released. With the PCP, the deadlines of all the hard real time transactions can be guaranteed for a given workload and system configuration. Besides the concurrency control protocols proposed for hard real time transaction systems, various protocols were proposed for soft and firm RTDBS, e.g. [4,11,12]. They used different heuristics to resolve data conflicts between transactions with different priorities. Although these protocols may not guarantee transaction deadlines, they can largely reduce the number of deadline violations. Although various concurrency control protocols were proposed in ....

....is resolved. On the other hand, if the lock requesting transaction is a lower priority transaction, it will be blocked until the higher priority transaction releases the lock. Aborting is also used in the optimistic concurrency control protocols to resolve data access conflicts in RTDBS, e.g. [4,12,19,20,21]. With optimistic concurrency control, the resolution of data conflicts is often delayed until a transaction has finished all of its operations. A validation test is performed to ensure that the resulted schedule is serializable if the validating transaction is allowed to commit. Various ....

[Article contains additional citation context not shown here]

Lee, J. (1994) Concurrency Control Algorithms for Real-time Database Systems. Ph.D. Thesis, Department of Computer Science, Univeristy of Virginia.

.... [Haritsa et al. 1990b] Haritsa et al. 1992] Haritsa et al. 1993] Hong et al. 1993] Huang et al. 1989] Huang et al. 1991a] Huang et al. 1991b] Huang et al. 1992] Kim et al. 1990] Kim Srivastava 1991] Kuo Mok 1992] Lam et al. 1995] Lee Son 1993] Lee Son 1994] [Lee Son 1995], Lin Son 1990] Sha et al. 1988] Sha et al. 1990] Sha et al. 1991] Son 1989] Son Chang 1990] Son Lee 1990] Son 1990] Son et al. 1992a] Son et al. 1992b] Son et al. 1992d] Son et al. 1992e] Son Park 1993] Son Kouloumbis 1993] Tseng Chin 1993] Ulusoy ....

J. Lee, S.H. Son `Concurrency Control Algorithms for Real-Time Database Systems ', Performance of Concurrency Control Algorithms in Centralized Database Systems, V. Kumar (ed.), Prentice-Hall, Englewood Cliffs, NJ, 1995.

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Lee, J. and Son, S.H. (1995) Concurrency Control Algorithms for Real-Time Database Systems, in Performance of Concurrency Control Mechanisms in Centralized Database Systems (ed. Vijay Kumar), Prentice Hall, 429-60.

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Juhnyoung Lee and Sang H. Son. "Concurrency Control Algorithms for Real-Time Database Systems " in "Performance of Concurrency Control Mechanisms in Centralized Database Systems," Vijay Kumar (editor), Prentice Hall 1995 (to appear).

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Lee, J. and Son, S.H. (1995) Concurrency Control Algorithms for Real-Time Database Systems, in Performance of Concurrency Control Mechanisms in Centralized Database Systems (ed. Vijay Kumar), Prentice Hall, 429-60.

....a range of transaction arrival rates. The goal of the analysis is to show the variation in miss percentage for varying capacity of the covert channel. 8. 1 Simulation Model Central to the simulation model is a single site disk resident database system operating on shared memory multiprocessors [8]. The system consists of a diskbased database and a main memory cache. The unit of database granularity is the page. When a transaction needs to perform an operation on a data item it accesses a page. If the page is not found in the cache, it is read from disk. CPU or disk access is through an ....

Juhnyoung Lee and Sang H. Son. "Concurrency Control Algorithms for Real-Time Database Systems " in "Performance of Concurrency Control Mechanisms in Centralized Database Systems," Vijay Kumar (editor), Prentice Hall 1995 (to appear) .

....The goal of the analysis is to show the variation in miss percentage for varying amounts of mutual information transferred through the covert channel. 9. 1 Simulation Model Central to the simulation model is a single site disk resident database system operating on sharedmemory multiprocessors [15]. The system consists of a disk based database and a main memory cache. The unit of database granularity is the page. When a transaction needs to perform an operation on a data item it accesses a page. If the page is not found in the cache, it is read from disk. CPU or disk access is through an ....

J. Lee and S.H. Son. "Concurrency Control Algorithms for Real-Time Database Systems," Performance of Concurrency Control Mechanisms in Centralized Database Systems, Vijay Kumar, ed., Prentice Hall, 1995, pp. 429-460.

No context found.

Juhnyoung Lee and Sang H. Son. "Concurrency Control Algorithms for Real-Time Database Systems" in "Performance of Concurrency Control Mechanisms in Centralized Database Systems", V. J. Kumar (editor), Prentice Hall 1996, pp 429-457.

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