When two or more scalar subtrees in an execution plan are directed towards the same data set, but request different data from the data set, the two subtrees are replaced in the execution plan with a new subtree which queries the data set only once. This new query to the data set covers all data required by the different subtrees. A pivoting step then is used to separate the data which would have been sought by each subtree. The pivoting step also yields data in the same form as would have resulted from the original subtrees.