SqlBracketBuilder open = query.filter().and().open();
open.column("u", "value").isNotNull();
open.or();
open.column("b", "value").isNotNull();
open.close();
query.groupBy("t.ctx");
return query.toString();
}
private SqlQueryBuilder buildCountQuery(RdbmsResource subj, RdbmsURI pred, RdbmsValue obj,
RdbmsResource... ctxs)