我有一个层次结构配置单元表，有两列，父列和子列。我需要获取与父记录关联的所有子体的列表。请注意，hive/imapala中不支持递归sql。

Source Table
+----+-----------+
| Parent | Child |
+----+-----------+
|  a     |     b |
|  b     |     c |
|  c     |     d |
|  d     |     e |
|  e     |     f |
|  f     |     x |
+----+-----------+

Expected Result:
+----+-----------+
| Parent | Child |
+----+-----------+
|  a     |     b |  // As b is the child of a, all the descendants of b 
|  a     |     c |  // are also descendants of a. 
|  a     |     d |
|  a     |     e |
|  a     |     f |
|  a     |     x |
|  b     |     c |  // As c is the child of b, all the descendants of c 
|  b     |     d |  // are also descendants of b.
|  b     |     e |
|  b     |     f |
|  b     |     x |
|  c     |     d |
|  c     |     e |
|  c     |     f |
|  c     |     x |
|  d     |     e |
|  d     |     f |
|  d     |     x |
|  e     |     f |
|  e     |     x |
|  f     |     x |
+----+-----------+

谢谢您！