When applied to a select with no aggregation or order by, this causes the select to produce results in an order that may vary between consecutive executions and may not correspond to the order of any index. In a cluster situation, running a query in this manner may be up to several times more efficient. This is not the default since SQL and SPARQL require that two consecutive executions of a query return the same results in the same order even if no order by is specified. Selects that contain aggregation or order by evaluate the part which generates input to the aggregation or order in this manner automatically. This option affects the select at the end of which it occurs and all selects inside it.

example:

select a.row_no from t1 a, t1 b wherea.row_no = 1 + b.row_no option (any order);