G. Diehr and A. N. Saharia. Estimating block accesses in database organizations. IEEE Transactions on Knowledge and Data Engineering, 6(3), 1994.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....storage layer. When a user query is submitted to the system (often concurrently with others) it is decomposed into a number of requests for blocks that need to be retrieved from disk (seconday and or tertiary) Typically, these blocks are randomly distributed over the various storage devices ([6, 7]) Some of the requested blocks may already reside in primary memory. For the rest of the cache missed blocks, the query optimizer needs to know what is the expected retrieval cost. Such an information will then be used in order to compute the best access plan in serving the query, which typically ....

George Diehr and Aditya N. Saharia, "Estimating Block Accesses in Database Organizations", IEEE Transactions on Knowledge and Data Engineering, pp. 497-499, vol 6, no. 3, June 1994.

.... uniform distribution [15] An approximation to Yao s formula was presented by Whang et al. 14] A study of errors when using Yao s formula with non uniform distribution and non uniform block size was performed by Luk [6] Diehr and Saharia studied upper and lower bounds for the Yao function in [3]. Common for all these models are that they assume unlimited buffer. Mackert and Lohman modeled index scans with limited buffer [7] but did not consider hot spots, only uniformly completely random access to an unclustered index. An extension of this study was performed by Swami and Schiefer ....

G. Diehr and A. N. Saharia. Estimating block accesses in database organizations. IEEE Transactions on Knowledge and Data Engineering, 6(3), 1994.

....by C i :A j and corresponds to the number of records to be selected in Equation (12) Since Equation (12) involves an iterative form, the computation cost can be excessively high as k becomes large. Approximation formulas for faster evaluation are presented in Whang et al. 23] and Diehr et al. [5]. 264 Wan Sup Cho et al. 4.4. Cardinalities of Intermediate Results for N way Joins In this section, we estimate intermediate results cardinalities for n way joins (nested predicates involving n classes) by using the cardinalities of unconditional joins and selectivity factors presented in ....

G. Diehr and A. N. Saharia. Estimating block accesses in database organizations. IEEE Trans. on Knowledge and Data Engineering, 6(3):497--499 (1994).

....Finally, in Section 10, we conclude the report and indicate topics for future work. 2 Related Work There have been several approaches to estimate the number of page accesses in the case of nonhierarchical files [3, 14, 13] and studies of the characteristics and validity of these estimates [10, 6]. However, they have not taken access pattern and buffering into account. Accesses have been assumed to be uniform, and an infinite buffer has been assumed, where only the first access to a page is counted. Recently, other approximations have been developed, the most interesting is the work done ....

G. Diehr and A. N. Saharia. Estimating block accesses in database organizations. IEEE Transactions on Knowledge and Data Engineering, 6(3), 1994.

....referred to by C i :A j and corresponds to the number of records to be selected in Eq. 12) Since Eq. 12) involves an iterative form, the computation cost can be excessively high as k becomes large. Approximation formulas for faster evaluation are presented in Whang et al. 23] and Diehr et al. [5]. 44 Wan Sup Cho et al. 4.4. Cardinalities of Intermediate Results for N way Joins In this section, we estimate intermediate results cardinalities for n way joins (nested predicates involving n classes) by using the cardinalities of unconditional joins and selectivity factors presented in ....

G. Diehr and A. N. Saharia. Estimating block accesses in database organizations. IEEE Trans. on Knowledge and Data Engineering, 6(3):497--499 (1994).

....computed by using a formula that was independently derived by Waters [Wat76] and Yao [Yao77] The formula was originally proposed for a problem in a different context. In order to avoid iterative computations several approximations of the formula have been proposed in the literature [Car75, Wat76, DS94] In [DS94] a upper bound and a lower bound of the formula were derived that are both accurate approximations. By using the upper bound, the number of target cylinders is approximately given as x = C F (1 Gamma (1 Gamma 1 C F ) N 2 (1 Gamma PC PC C F Gamma N 1 ) N 2 ) Cyl ....

....using a formula that was independently derived by Waters [Wat76] and Yao [Yao77] The formula was originally proposed for a problem in a different context. In order to avoid iterative computations several approximations of the formula have been proposed in the literature [Car75, Wat76, DS94] In [DS94] a upper bound and a lower bound of the formula were derived that are both accurate approximations. By using the upper bound, the number of target cylinders is approximately given as x = C F (1 Gamma (1 Gamma 1 C F ) N 2 (1 Gamma PC PC C F Gamma N 1 ) N 2 ) Cyl 840 TC 20 PT ....

G. Diehr and A. Saharia. Estimating block accesses in database organizations. IEEE Transactions on Knowledge and Data Engineering, 6(3):497--499, 1994.

....and index sizes affects the performance. Finally, in Sect. 10, we conclude the paper. 2 Related Work There have been several approaches to estimate the number of page accesses in the case of non hierarchical files [3, 13, 14] and studies of the characteristics and validity of these estimates [6, 9]. However, they have not taken access pattern and buffering into account. Accesses have been assumed to be uniform, and an infinite buffer has been assumed, where only the first access to a page is counted. Recently, other approximations have been developed, the most interesting is the work done ....

G. Diehr and A. N. Saharia. Estimating block accesses in database organizations. IEEE Transactions on Knowledge and Data Engineering, 6(3), 1994.

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G. Diehr and A. N. Saharia. Estimating block accesses in database organizations. IEEE Transactions on Knowledge and Data Engineering, 6(3), 1994.

No context found.

G. Diehr and A. N. Saharia. Estimating block accesses in database organizations. IEEE Transactions on Knowledge and Data Engineering, 6(3), 1994.

No context found.

G. Diehr and A. N. Saharia. Estimating block accesses in database organizations. IEEE Transaction on Knowledge and Data Engineering, Vol. 6, No. 3, June 1994.

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