使用 Redis 解决“树”形数据的复杂查询

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使用 Redis 解决“树”形数据的复杂查询

2017 年 9 月 4 日 数据库开发

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来源：qiujiayu

my.oschina.net/u/1469495/blog/1504818

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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。

想了一短时间后，想出了下面的方案：

一、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 |

二、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](https://my.oschina.net/azibug)

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