hadoop - Hive - 将层次结构表展平为多个级别

Question

我的层次结构表的父子关系最高级别为 15。我需要找出每个父节点的子节点的所有级别。我尝试过递归查询，但它在 Hive 和 Impala 中不起作用。请提出一些查询来解决这个问题。

+---------------+----------------+
|parent_node_id | child_node_id  |
+---------------+----------------+
|  C1           |    C11         |
+---------------+----------------+
|  C11          |    C12         |
+---------------+----------------+
|  C12          |    123         |
+---------------+----------------+
|  C12          |    456         |
+---------------+----------------+
|  P1           |    C1          |
+---------------+----------------+
|  P1           |    C2          | 
+---------------+----------------+
|  P2           |    C3          | 
+---------------+----------------+


+-------+----------+
| node  | balance  |
+-------+----------+
|  123  |  100     |
+-------+----------+
|  456  |  150     |
+-------+----------+
|  C2   |  400     |
+-------+----------+
|  C3   |  200     |
+-------+----------+

输出数据:

+---------------+-------------+---------+----------+----------+
|Parent_node_id |   Level 1   | Level 2 | Level 2  | Level3   | 
+---------------+-------------+---------+----------+----------+
|  P1           |    C1       | C11     |  C12     |  123     |
+---------------+-------------+---------+----------+----------+
|  P1           |    C1       | C11     |  C12     |  456     |
+---------------+-------------+---------+----------+----------+
|  P1           |    C2       | NULL    |  NULL    |  NULL    |
+---------------+-------------+---------+----------+----------+
|  P2           |    C3       | NULL    |  NULL    |  NULL    |
+---------------+-------------+---------+----------+----------+


+-------+----------+
| node  | balance  |
+-------+----------+
|  123  |  100     |
+-------+----------+
|  456  |  150     |
+-------+----------+
|  C12  |  250     |
+-------+----------+
|  C11  |  250     |
+-------+----------+
|  C1   |  250     |
+-------+----------+
|  P1   |  650     |
+-------+----------+
|  C2   |  200     |
+-------+----------+
|  P2   |  200     |
+-------+----------+

Answer 1

既然您知道层次结构中可以存在的最大关系，

下面是查询-

hive> select * from hier;
OK
parent child child_desc
C1      C11     Party
C1      C111    Placement
C111    C1111   XM
C12     C121    Brand
C2      C12     Equity
XN12    C1      Private
XN12    C2      Public
Time taken: 0.123 seconds, Fetched: 7 row(s)

查询-

with lvl1 as
(
select p1.parent, p1.child child1, p1.child_desc child_desc1, p2.child child2, p2.child_desc child_desc2
from hier p1 left outer join hier p2
on p1.child = p2.parent
)
, lvl2 as
(
select lvl1.parent, lvl1.child1, lvl1.child_desc1, lvl1.child2 child2, lvl1.child_desc2, p3.parent p2, 
p3.child as child3, p3.child_desc child_desc3
from lvl1 left outer join hier p3 on nvl(lvl1.child2,'A') = nvl(p3.parent,'A')
)
, lvl3 as
(
select lvl2.parent, lvl2.child1 child1, lvl2.child_desc1, lvl2.child2 child2, lvl2.child_desc2, 
lvl2.child3 hild3, lvl2.child_desc3, p3.child as child4, p3.child as child_desc4
from lvl2 left outer join hier p3 on nvl(lvl2.child3,'A') = nvl(p3.parent,'A')
)
select * from lvl3;

C1      C11     Party   NULL    NULL    NULL    NULL    NULL    NULL
C1      C111    Placement       C1111   XM      NULL    NULL    NULL    NULL
C111    C1111   XM      NULL    NULL    NULL    NULL    NULL    NULL
C12     C121    Brand   NULL    NULL    NULL    NULL    NULL    NULL
C2      C12     Equity  C121    Brand   NULL    NULL    NULL    NULL
XN12    C1      Private C11     Party   NULL    NULL    NULL    NULL
XN12    C1      Private C111    Placement       C1111   XM      NULL    NULL
XN12    C2      Public  C12     Equity  C121    Brand   NULL    NULL

上面的查询是针对level-3的，你可以将它复制到level-15。

我已经测试了 3 个级别的上述查询。

hive> select * from hier;
OK
parent child
C1      C11
C11     C12
C12     123
P1      C1
P2      C2

o/p-

C1      C11     C12     123     NULL
C11     C12     123     NULL    NULL
C12     123     NULL    NULL    NULL
P1      C1      C11     C12     123
P2      C2      NULL    NULL    NULL

如果您想要 n 级查询并且不想对查询进行硬编码，则需要编写一些脚本(需要大量工作)来创建查询或多次迭代相同的查询。

希望对你有帮助