Currently in Bonsai each projection is implemented as a separate EvaluationNode. We have an existing optimisation which tries to convert each projection into a SargableNode, and push it down into collection/index scan. However, if the projections contains residual expressions, we may end up with a physical plan containing a stack of EvaluationNodes, which eventually will be lowered into a stack of SBE project operators. We will need to investigate performance overhead of having a stack of projections in an SBE plan and try to optimize it by merging the EvalNodes into a single evaluation node (a new type of an ABT node) with combined projections.