Puede utilizar las funciones analíticas LEAD y LAG para acceder a la fila anterior y siguiente de un conjunto de resultados y luego usar eso para ver si hay cambios.
SQL> ed
Wrote file afiedt.buf
1 with t as (
2 select date '2011-10-22' dt, 3.2 price from dual union all
3 select date '2011-10-23', 3.4 from dual union all
4 select date '2011-10-24', 3.4 from dual union all
5 select date '2011-10-25', 3.5 from dual union all
6 select date '2011-10-26', 3.4 from dual union all
7 select date '2011-10-27', 3.2 from dual union all
8 select date '2011-10-28', 3.2 from dual
9 )
10 select sum(is_change)
11 from (
12 select dt,
13 price,
14 lag(price) over (order by dt) prior_price,
15 (case when lag(price) over (order by dt) != price
16 then 1
17 else 0
18 end) is_change
19* from t)
SQL> /
SUM(IS_CHANGE)
--------------
4
