We calibrated first version of Cost Model with some simplifications in mind, one of them was that the cost of an ABT node depends on the number of incoming (processed) documents. As we highlighted in the design doc this assumption not correct for all ABT nodes.

The following nodes can be relatively easy to improve:

• Filter node - we need to take into account number of predicates in its expression
• Evaluation node in case of simple projections (show/hide fields) by taking into account number of the fields.