Major Description
A correlation path is defined as the sub-tree of all the operators that are on the path from the operator hosting the correlated expressions up to the operator producing the correlated values.
We want to support set operators such as union and intercept to be on correlation paths by adding them in DecorrelateInnerQuery. Please see page 391 for more details: https://dl.gi.de/bitstream/handle/20.500.12116/2418/383.pdf
