Preserve user specified join type

[ghost]

Storing the join type for a joined table in a map. Later when computing the join clause, we look up in the map to get the user specified join type.

[ghost]

@Amareshwari updated pull req. pls check

[Amareshwari]

do we have to move the user given filter from join to where? Is it not possible to keep it in join clause itself? Somehow, i feel we should not touch user given filters.

[ghost]

This is only in case of right outer or left outer join. In that case it indicates where the filter would be executed. For ex - in case of left outer join, filter on the right table is pushed down in the join condition whereas filter on the left table is applied during scan, as its part of the where clause.