public BottomUpJoinIterator(EvaluationStrategy strategy, Join join, BindingSet bindings)
throws QueryEvaluationException {
leftIter = strategy.evaluate(join.getLeftArg(), bindings);
rightIter = strategy.evaluate(join.getRightArg(), bindings);
joinAttributes = join.getLeftArg().getBindingNames();
joinAttributes.retainAll(join.getRightArg().getBindingNames());
hashTable = null;
}
@Override
public void meet(Join join) {
if (join.getLeftArg().getBindingNames().containsAll(filterVars)) {
// All required vars are bound by the left expr
join.getLeftArg().visit(this);
} else if (join.getRightArg().getBindingNames().containsAll(filterVars)) {
// All required vars are bound by the right expr
join.getRightArg().visit(this);
} else {
relocate(filter, join);
}
}
public long getCardinality(Join join, BindingSet bindings) {
long card1 = getCardinality(join.getLeftArg(), bindings);
long card2 = getCardinality(join.getRightArg(), bindings);
double sel = 0.5;
return (long) (card1 * card2 * sel);
}