期刊名称：Journal of Computer Sciences and Applications
印刷版ISSN：2328-7268
电子版ISSN：2328-725X
出版年度：2014
卷号：2
期号：2
页码：31-35
DOI：10.12691/jcsa-2-2-3
语种：English
出版社：Science and Education Publishing
摘要：The nested structured queries as well as nested iteration as operator in both the logical and physical query algebra have been sometimes neglected in research. Interesting issues arise if multiple invocations of the same nested computation affect each other, e.g., the first invocation warms up the I/O buffer for subsequent ones. Other interesting issues arise if different nested computations compete for resources, e.g., I/O buffer or memory for sort and hash operations within inner queries. Nested computations are very important in practice, both because queries are authored using nested structured queries and because nested iteration based on index-to-index navigation often is the best execution plan. Therefore, nested computations could be a very fruitful research topic, both execution and optimization, and could probably also benefit from more dynamic and adaptive techniques than those in use today. While most resource issues have relatively little impact on optimal plan choices (even if they affect the ranking among different plans of fairly similar costs), one issue that is crucial in practice but usually ignored in academic research is the effect of buffer hits and faults in complex query plans. However, a conceptual model may be needed of nested queries that are substantially simpler, e.g., based on algebra expressions with a table of parameter values. In this paper it is aimed to find location of local minima of particle, random velocities of particles considering the relation schemes. The query plans related to relation schemes may be represented as particles. The query is optimized at compile time by that the complete query execution plans may be generated. The function evaluation of particles represented in terms of query plans in the relation schemes is planned to be done by considering random population of continuous values and velocities.
