Problem with CONNECT BY NOCYCLE in oracle 10.2.0.4

Question

Hi,
When I run the below query in 10.2.0.2 it is executing in fraction of seconds, but while executing the same query in 10.2.0.4 it is running indefinitely.
Please check the below query and is there any issue with CONNECT BY NOCYCLE in 10.2.0.4 and also please help me to get out of this problem in 10.2.0.4.
SELECT 1 type_num, r.NAME root_name, r.DATA_GROUP root_data_group,
NULL child_name, NULL child_data_group, NULL child_type,
NULL facility_type
FROM DATA_GROUP r
WHERE r.DATA_GROUP = (SELECT MIN (DATA_GROUP)
FROM DATA_GROUP
WHERE node_type = 'R' AND tree_type = 'C'
GROUP BY tree_type)
UNION ALL
SELECT DISTINCT 2 type_num, NULL root_name, NULL root_data_group,
dg_child.NAME AS child_name,
dgl.DATA_GROUP AS child_data_group,
dg_child.node_type AS child_type, f.TYPE AS facility_type
FROM DATA_GROUP_LINK dgl, DATA_GROUP dg_child, FACILITY f
WHERE dgl.DATA_GROUP = dg_child.DATA_GROUP
AND dg_child.node_type = 'F'
AND f.facility_num = dg_child.DATA_GROUP
START WITH dgl.parent_data_group IN (
(SELECT DATA_GROUP
FROM DATA_GROUP_SYSTEM_USER
WHERE system_user_num = 1000088400 AND is_active = 'Y'
UNION
SELECT 1016189 AS DATA_GROUP
FROM DUAL))
CONNECT BY NOCYCLE dgl.parent_data_group = dgl.DATA_GROUP;
Thanks,
Mahi

Answer 1

Find and read the thread about when queries take too long.
Something is different between the systems, possibly
* indexing
* volume of data
* connect-by structure in table data
* initialization or session settings