Institutional Repository
Technical University of Crete
Technical University of Crete
EN
|
EL
| URI: | http://purl.tuc.gr/dl/dias/FA5231DA-D168-4CB2-AA1A-FDAF32CF9E93 | ||
| Year | 1984 | ||
| Type of Item | Peer-Reviewed Journal Publication | ||
| License |
|
||
| Bibliographic Citation | S. Christodoulakis, "Estimating block selectivities", Information Systems, vol. 9, no. 1, pp. 69-79, 1984. doi: 10.1016/0306-4379(84)90017-6 https://doi.org/10.1016/0306-4379(84)90017-6 | ||
| Appears in Collections |
In many data base performance studies there is a need to estimate the number of records of a file which qualify in a query, as well as the number of blocks of secondary storage which contain these records. In this paper we present a model of data base contents and data placement on devices. We extend a multivariate statistical model that was used for the estimation of record selectivities in [5] to model the distribution of records that qualify in a query among the blocks of secondary storage. Then we show how to obtain estimates of block selectivities and we compare our estimates with the estimates of previous models.
Copyright © DIAS 2013
