使用Redis解決「樹」形數據的複雜查詢

時間 2019-11-15

標籤使用 redis 解決數據複雜查詢欄目 Redis 简体版

原文原文鏈接

使用Redis解決「樹」形數據的複雜查詢

最近因業務須要，研究了一下樹數據結果的存儲及查詢解決方案。最初的想法是使用neo4j,但是在網上看了一下開源的不支持集羣，感受用的人很少。node

網上也查了一些樹形結構數據存儲方案但每種實現方案都有它的必定侷限性。redis

想了一短期後，想出了下面的方案：數據庫

1、由於複雜的查詢都由Redis來處理，因此數據庫表的設計就變得很是簡單：tree 表json

字段名稱	數據類型	備註說明
id	int	主鍵
parent_id	int	上級節點ID

2、Redis的數據存儲方案：測試

把表的數據存儲到一個Hash表中，使用表中的id值作爲此hash表的key, value值爲：優化

{
   id: 10,
   parentId: 9,
   childIds: [11]
}

代碼實現

爲了簡化測試，這裏只演示Redis相關的操做lua

Tree 類定義spa

public class Tree {
     private Integer id;
     private String name;
     private Integer parentId;
     private List<Integer> childIds;
 }

往Redis中添加測試數據：.net

[@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 代碼的實現設計

在Lua中使用遞歸時，須要使用「尾調用」來優化代碼。關於尾調用的知識，你們能夠上網去搜索。

獲取全部子節點 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 {}

獲取全部子節點數目 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

獲取全部子節點數目 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 {}

獲取全部子節點數目 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

以上代碼由於使用了「尾調用」，因此變得相對比較複雜