public Relation multiply(Relation that) {
ColumnIndexesImpl c = new ColumnIndexesImpl(this.columns());
c.addAll(that.columns());
ColumnIndexesImpl ec = new ColumnIndexesImpl(this.expandedColumns());
ec.addAll(that.expandedColumns());
return makeNew(Utils.cartProd(this.formula, that.formula), c, ec);
}
private Relation select(Iterable<String> sel, ColumnIndexesImpl c) {
return this.select(Iterables.toArray(sel, String.class), c);