表格B-树从lmdb数据库返回

Question

我正在遍历一棵树并形成一个(key:value) lmdb数据库。我正在努力使树返回迭代lmdb。

1. Can one建议如何通过遍历数据库来形成树，这是( key : value) NoSQL?
2. lmdb键是按字典排序的。有什么方法可以阻止它，保持秩序，这样可以帮助树形回到

。

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用于创建lmdb数据库的代码：

import lmdb
import pickle

class node:
    def __init__(self, info, level = 0):
        self._info = info
        self.level = level

#               A:1
#             /   \
#          B:2       C:3
#       /            \
#      D:4            G:7
#   /     \
# E:5       F:6
#  "A" : serialized node-A
# "A.B" : serialized node-B
# "A.C" : serialized node-c
# "A.B.D" : serialized node - D
# "A.C.G" : serialized node - G
# "A.B.D.E" : serialized node - E
# "A.B.D.F" : serialized node - F

#Form the lmdb from Tree
env = lmdb.open("test.lmdb")
txn = env.begin(write=True)
new_node = node({"A":1})
txn.put(pickle.dumps("A"), pickle.dumps(new_node))
new_node = node({"B":2}, 1)
txn.put(pickle.dumps("A.B"), pickle.dumps(new_node))
new_node = node({"C":3}, 1)
txn.put(pickle.dumps("A.C"), pickle.dumps(new_node))
new_node = node({"D":4}, 2)
txn.put(pickle.dumps("A.B.D"), pickle.dumps(new_node))
new_node = node({"G":7}, 2)
txn.put(pickle.dumps("A.C.G"), pickle.dumps(new_node))
new_node = node({"E":5}, 3)
txn.put(pickle.dumps("A.B.D.E"), pickle.dumps(new_node))
new_node = node({"F":6}, 3)
txn.put(pickle.dumps("A.B.D.F"), pickle.dumps(new_node))

迭代数据库代码：

env = lmdb.open("test.lmdb")
txn = env.begin()
cursor = txn.cursor()
for idx, value in enumerate(cursor):
    a,b = pickle.loads(value[0]), pickle.loads(value[1])
    print(a,b)

Answer 1

我终于想出了如何形成这棵树。

#form Tree from lmdb
cursor = txn.cursor()
root = Node()
for idx, value in enumerate(cursor):
    a,b = pickle.loads(value[0]), pickle.loads(value[1]) # a: string b: obj
    print(a,b)
    tree_node = root #always start with root
    _xl = a.split(".") #list of paths
    if len(_xl) == 1:
        setattr(root,a,b)
    else:
        _il = _xl[:len(_xl) - 1]  # all path except child
        _child_name = _xl[-1]
        #discover parent
        parent = root
        for item in _il:
            parent = getattr(parent,item)
        setattr(parent, _child_name, b)