c-treeACE SQL ON Clause Join Order Optimizations

It was possible, while the c-treeACE SQL engine was forming the join order, the sorting requirement was not considered. The optimizer has been modified to take into consideration any sorting requirements during the join order optimization phase.

Specifically, predicates in the ON clause, were not pushed down the right branch of the outer join node, however, predicates from the WHERE clause were pushed down to the right branch of a Left Outer Join (LOJ) and the LOJ converted to an inner join. The modifications now allow pushing down of predicates from the ON clause to the right branch of the LOJ, however, without converting the LOJ to Inner Join.