Ciaccia, P., Block Access Estimation for Clustered Data, IEEE Transactions on Knowledge and Data Engineering, Vol. 5(4), 1993.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....good behavior of the model. Keywords Relational database, projection, error estimate, combinatorial models, statistical profile, query optimization I. Introduction Optimization of relational database queries is a difficult problem that has received a lot of attention in the last two decades [8], 11] 18] 26] 33] The main motivation for this is that suboptimal strategies for query execution can have costs which are several orders of magnitude higher than the cost of the optimal strategy. Optimizers of relational database systems make use of statistical information to estimate the ....

....Differences between jR 0 [Y ]j e GP and jR 0 [Y ]j e GP FD are completely negligible when, as is usually the case, dZ is large, 3 The values 4,200 and 28:99 have been determined by means of the functions we introduce in the next section. since (3) reduces to (4) as dZ tends to infinity [8]. For instance with n = 200, dY = 500, and dZ = 20, the two models estimates differ by only 0:8 . We note that (4) is also the model proposed in [12] when the single functional dependency Z Y holds in R[X] 4 This fact has been used in setting up simulations as follows: we consider a ....

P. Ciaccia. Block access estimation for clustered data. IEEE Transactions on Knowledge and Data Engineering, 5(4):712-- 718, Aug. 1993.

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Ciaccia, P., Block Access Estimation for Clustered Data, IEEE Transactions on Knowledge and Data Engineering, Vol. 5(4), 1993.

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