目前直接explain计划还是逻辑计划，并不是真实执行sql后的信息，4.x版本可以仍sql monitor来关测
执行完query(加上hint
/+monitor/)
可以执行完以后select last_trace_id()获取trace_id， 然后执行
select plan_line_id, plan_operation, sum(output_rows), sum(STARTS) rescan, min(first_refresh_time) open_time, max(last_refresh_time) close_time, max(last_refresh_time) - min(first_refresh_time) open_close_cost, min(first_change_time) first_row_time, max(last_change_time) last_row_eof_time, max(last_change_time) - min(first_change_time) rows_cost, count(1) from oceanbase.GV$SQL_PLAN_MONITOR where trace_id = ‘Yxxx’ group by plan_line_id, plan_operation order by plan_line_id;