最近因业务需要，研究了一下树数据结果的存储及查询解决方案。
最初的想法是使用neo4j,可是在网上看了一下开源的不支持集群，感觉用的人不多。
网上也查了一些 树形结构数据存储方案 但每种实现方案都有它的一定局限性。
想了一段时间后，想出了下面的方案：
将原始数据简单保存到数据库中，而对于复杂的查询，使用Lua+Redis来实现。
-
因为复杂的查询都由Redis来处理，所以数据库表的设计就变得非常简单：tree 表
字段名称 数据类型 备注说明 id int 主键 parent_id int 上级节点ID -
Redis的数据存储方案：
把表的数据存储到一个Hash表中，使用表中的id值做为此hash表的key, value值为：
{ id: 10, parentId: 9, childIds: [11] }
代码实现
为了简化测试，这里只演示Redis相关的操作
-
Tree 类定义
public class Tree { private Integer id; private String name; private Integer parentId; private List<Integer> childIds; } -
往Redis中添加测试数据：
@Test public void addTestData() throws Exception { String key = "tree-test-key"; Tree tree = new Tree(); List<Integer> childIds = new ArrayList<>(); int max = 100000 tree.setChildIds(childIds); for (int i = 0; i < max; i++) { tree.setId(i); tree.setName("tree" + i); if (i > 0) { tree.setParentId(i - 1); } childIds.clear(); if(i < (max - 1)){ childIds.add(i + 1); } redis.setHash(key, "" + i, JsonUtil.toJson(tree)); } } Lua 代码的实现
在Lua中使用递归时，需要使用“尾调用”来优化代码。关于尾调用的知识，大家可以上网去搜索。
获取所有子节点 get-tree-childs.lua
local treeKey = KEYS[1]
local fnodeId = ARGV[1]
local function getTreeChild(currentnode, t, res)
if currentnode == nil or t == nil then
return res
end
local nextNode = nil
local nextType = nil
if t == "id" and (type(currentnode) == "number" or type(currentnode) == "string") then
local treeNode = redis.call("HGET", treeKey, currentnode)
if treeNode then
local node = cjson.decode(treeNode)
table.insert(res, treeNode)
if node and node.childIds then
nextNode = node.childIds
nextType = "childIds"
end
end
elseif t == "childIds" then
nextNode = {}
nextType = "childIds"
local treeNode = nil
local node = nil
local cnt = 0
for _, val in ipairs(currentnode) do
treeNode = redis.call("HGET", treeKey, tostring(val))
if treeNode then
node = cjson.decode(treeNode)
table.insert(res, treeNode)
if node and node.childIds then
for _, val2 in ipairs(node.childIds) do
table.insert(nextNode, val2)
cnt = cnt + 1
end
end
end
end
if cnt == 0 then
nextNode = nil
nextType = nil
end
end
return getTreeChild(nextNode, nextType, res)
end
if treeKey and fnodeId then
return getTreeChild(fnodeId, "id", {})
end
return {}
获取所有子节点数目 get-tree-childs-cnt.lua
local treeKey = KEYS[1]
local fnodeId = ARGV[1]
local function getTreeChildCnt(currentnode, t, res)
if currentnode == nil or t == nil then
return res
end
local nextNode = nil
local nextType = nil
if t == "id" and (type(currentnode) == "number" or type(currentnode) == "string") then
local treeNode = redis.call("HGET", treeKey, currentnode)
if treeNode then
local node = cjson.decode(treeNode)
res = res + 1
if node and node.childIds then
nextNode = node.childIds
nextType = "childIds"
end
end
elseif t == "childIds" then
nextNode = {}
nextType = "childIds"
local treeNode = nil
local cnt = 0
for _, val in ipairs(currentnode) do
treeNode = redis.call("HGET", treeKey, tostring(val))
if treeNode then
local node = cjson.decode(treeNode)
res = res + 1
if node and node.childIds then
for _, val2 in ipairs(node.childIds) do
table.insert(nextNode, val2)
cnt = cnt + 1
end
end
end
end
if cnt == 0 then
nextNode = nil
nextType = nil
end
end
return getTreeChildCnt(nextNode, nextType, res)
end
if treeKey and fnodeId then
return getTreeChildCnt(fnodeId, "id", 0)
end
return 0
获取所有子节点数目 get-tree-parent.lua
local treeKey = KEYS[1]
local nodeId = ARGV[1]
local function getTreeParent(treeKey, res, nodeId)
if nodeId == nil or not (type(nodeId) == "number" or type(nodeId) == "string") then
return res
end
local treeNode = redis.call("HGET", treeKey, nodeId)
local nextNodeId = nil
if treeNode then
local node = cjson.decode(treeNode)
table.insert(res, treeNode)
if node then
nextNodeId = node.parentId
end
end
return getTreeParent(treeKey, res, nextNodeId)
end
if treeKey and nodeId then
return getTreeParent(treeKey, {}, nodeId)
end
return {}
获取所有子节点数目 get-tree-parent-cnt.lua
local treeKey = KEYS[1]
local nodeId = ARGV[1]
local function getTreeParentCnt(treeKey, nodeId, res)
if nodeId == nil or not (type(nodeId) == "number" or type(nodeId) == "string") then
return res
end
local treeNode = redis.call("HGET", treeKey, nodeId)
local nextNodeId = nil
if treeNode then
local node = cjson.decode(treeNode)
res = res + 1
if node then
nextNodeId = node.parentId
end
end
return getTreeParentCnt(treeKey, nextNodeId, res)
end
if treeKey and nodeId then
return getTreeParentCnt(treeKey, nodeId, 0)
end
return 0
以上代码因为使用了“尾调用”，所以变得相对比较复杂
总结
此方案相对比较灵活，能支持相对比较大量的数据。
缺点：过于依赖Redis。数据同步会麻烦些，好在操作不是很复杂。
