return null;
case NodeConstants.Types.SET_OP:
Operation setOp = (Operation) node.getProperty(NodeConstants.Info.SET_OPERATION);
boolean useAll = ((Boolean) node.getProperty(NodeConstants.Info.USE_ALL)).booleanValue();
if(setOp == Operation.UNION) {
RelationalNode unionAllNode = new UnionAllNode(getID());
if(useAll) {
processNode = unionAllNode;
} else {
SortNode sNode = new SortNode(getID());
boolean onlyDupRemoval = node.hasBooleanProperty(NodeConstants.Info.IS_DUP_REMOVAL);
sNode.setMode(onlyDupRemoval?Mode.DUP_REMOVE:Mode.DUP_REMOVE_SORT);
processNode = sNode;
unionAllNode.setElements( (List) node.getProperty(NodeConstants.Info.OUTPUT_COLS) );
processNode.addChild(unionAllNode);
}
} else {
JoinNode joinAsSet = new JoinNode(getID());
joinAsSet.setJoinStrategy(new MergeJoinStrategy(SortOption.SORT_DISTINCT, SortOption.SORT_DISTINCT, true));