Visitor that enables an update or delete statement to operate successfully over a sink operation (e.g. merge sort
join). Vanilla Derby handles this by adding a CurrentRowLocationNode as a ResultColumn to the top most
In order for this to work in Splice with our sink operations, a CurrentRowLocationNode is also used, but on the lower
level ProjectRestrictNodes, in particular those in the path to the leftmost leaf node. The row location of each row
to be updated can then be propagated to the top level update or delete statement.
This visitor is a no-op except for an update or delete statement above a sink operation, in which case the query plan
tree is mutated to provide the support described above. No additional nodes are added, but existing nodes like
ProjectRestrictNodes are modified.