The idea here is to do the following. 1) Make a small number of item classes reentrant. 2) Make a walker to see if item tree is reentrant. 3) Make the JOIN_TAB reentrant by small modifications (not the full split of its data). 4) Rely on cursor class in handler interface developed for Foreign Key 5) Simple threading mechanism 6) Test with a small number of queries The purpose of this task is to discover if the choosen method is viable and it's not yet the purpose to go for a full-fledged Parallel Query implementation.