Oracle HowTo:如何使用Leading提示改变表连接方式

SQL> SELECT /*+ leading(t_max) use_hash(t_max t_middle) */ COUNT (*)
  2    FROM t_small, t_max, t_middle
  3  WHERE t_small.object_id = t_middle.object_id
  4  AND t_middle.object_id = t_max.object_id
  5  /

Execution Plan
----------------------------------------------------------
   0      SELECT STATEMENT Optimizer=CHOOSE (Cost=262 Card=1 Bytes=12)
   1    0   SORT (AGGREGATE)
   2    1     HASH JOIN (Cost=262 Card=400 Bytes=4800)
   3    2       HASH JOIN (Cost=225 Card=113776 Bytes=910208)
   4    3         TABLE ACCESS (FULL) OF 'T_MAX' (Cost=151 Card=113792 Bytes=455168)
   5    3         TABLE ACCESS (FULL) OF 'T_MIDDLE' (Cost=39 Card=28447 Bytes=113788)
   6    2       TABLE ACCESS (FULL) OF 'T_SMALL' (Cost=2 Card=100 Bytes=400)