WITH t AS (
SELECT 1 id1, 111 id2, 1 is_change, 20 summ FROM DUAL UNION ALL
SELECT 1 id1, 111 id2, 0 is_change, 35 summ FROM DUAL UNION ALL
SELECT 1 id1, 111 id2, 0 is_change, 56 summ FROM DUAL UNION ALL
SELECT 1 id1, 111 id2, 0 is_change, 34 summ FROM DUAL UNION ALL
SELECT 1 id1, 111 id2, 0 is_change, 33 summ FROM DUAL UNION ALL
SELECT 1 id1, 111 id2, 1 is_change, 48 summ FROM DUAL UNION ALL
SELECT 1 id1, 111 id2, 0 is_change, 76 summ FROM DUAL UNION ALL
SELECT 1 id1, 111 id2, 0 is_change, 11 summ FROM DUAL UNION ALL
SELECT 2 id1, 333 id2, 1 is_change, 98 summ FROM DUAL UNION ALL
SELECT 2 id1, 333 id2, 0 is_change, 56 summ FROM DUAL UNION ALL
SELECT 2 id1, 333 id2, 0 is_change, 29 summ FROM DUAL UNION ALL
SELECT 2 id1, 333 id2, 0 is_change, 95 summ FROM DUAL)
SELECT * FROM t

ID1 ID2  IS_CHANGE  P   SUMM
1   111  1          1   20
1   111  0          1   35
1   111  0          1   56
1   111  0          1   34
1   111  0          1   33
1   111  1          2   48
1   111  0          2   76
1   111  0          2   11
2   333  1          3   98
2   333  0          3   56
2   333  0          3   29
2   333  0          3   95

SUM(is_change) OVER (ORDER BY id1,id2)