使用Linq对Hashtable和Dictionary<T,T>查询的效率比较

近期做版本迭代任务，有一个在店铺头部展示店主所在的城市名称和省份名称的需求,店主信息表中保存了店主所在的城市Id和省份Id，由于原有业务复杂，要尽量减少Sql执行时间，所以不考虑join城市地区详细表。于是考虑在集合类中处理。

是选择Hashtable还是Dictionary<T,T>呢？于是做了一个测试，代码清单如下:

 /// <summary>
     /// 城市信息
     /// </summary>
     public class CityInfo
     {
         public string CityName { get; set; }
         public string ProvinceName { get; set; }
     }
     /// <summary>
     /// 数据仓库和查找方法
     /// </summary>
     public static  class Respository
     {

         public static Hashtable Retrieve()
         {
             Hashtable data = new Hashtable();
             for (int i = ; i < ; i++)
             {
              data.Add(i+,"data"+i);
             }
             return data;
         }
         public static string Find(Hashtable data,int id)
         {
             var query = from item in data.Cast<DictionaryEntry>() where (int)item.Key == id select item.Value.ToString();
             return query.First();
         }

         public static Dictionary<int, string> SecondRetrieve()

         {
             Dictionary<int,string> data = new Dictionary<int,string>();
             for (int i = ; i < ; i++)
             {
                 data.Add(i + , "data" + i);
             }
             return data;
         }

         public static string SecondFind(Dictionary<int, string> data, int id)
         {
             var query = from item in data where (int)item.Key == id select item.Value;
             return query.First();
         }

         public static Dictionary<int, CityInfo> ThridRetrieve()
         {
             Dictionary<int, CityInfo> data = new Dictionary<int, CityInfo>();
             for (int i = ; i < ; i++)
             {
                 data.Add(i + ,  new CityInfo { CityName="CityName"+i, ProvinceName="ProvinceName"+i  });
             }
             return data;
         }

         public static CityInfo ThridFind(Dictionary<int, CityInfo> data, int id)
         {
             var query = from item in data where (int)item.Key == id select item.Value;
             return query.First();
         }
     }

测试入口:

 static void Main(string[] args)
         {
             {
                 Stopwatch stwtotal = new Stopwatch();
                 stwtotal.Start();
                 Hashtable data = Respository.Retrieve();
                 for (int i = ; i < ; i++)
                 {
                     Stopwatch stw = new Stopwatch();
                     stw.Start();
                     Random r = new Random();
                     string result = Respository.Find(data, r.Next(, )*i);
                     stw.Stop();
                     Console.WriteLine(result + "   FirstFindExecuteTime:" + stw.Elapsed.TotalMilliseconds+"ms");
                 }
                 stwtotal.Stop();
                 Console.WriteLine("测试数据总时间：" + stwtotal.Elapsed.TotalMilliseconds + "ms");
             }
             {
                 Stopwatch stwtotal = new Stopwatch();
                 stwtotal.Start();
                 Dictionary<int, string> data = Respository.SecondRetrieve();
                 for (int i = ; i < ; i++)
                 {
                     Stopwatch stw = new Stopwatch();
                     stw.Start();
                     Random r = new Random();
                     string result = Respository.SecondFind(data, r.Next(, )*i);
                     stw.Stop();
                     Console.WriteLine(result + "   SecondFindExecuteTime:" + stw.Elapsed.TotalMilliseconds+"ms");
                 }
                 stwtotal.Stop();
                 Console.WriteLine("测试数据总时间：" + stwtotal.Elapsed.TotalMilliseconds + "ms");
             }
             {
                 Stopwatch stwtotal = new Stopwatch();
                 stwtotal.Start();
                 Dictionary<int, CityInfo> data = Respository.ThridRetrieve();
                 for (int i = ; i < ; i++)
                 {
                     Stopwatch stw = new Stopwatch();
                     stw.Start();
                     Random r = new Random();
                     CityInfo result = Respository.ThridFind(data, r.Next(, ) * i);
                     stw.Stop();
                     Console.WriteLine(result.CityName + "   ThridFindExecuteTime:" + stw.Elapsed.TotalMilliseconds + "ms");
                 }
                 stwtotal.Stop();
                 Console.WriteLine("真实数据初始化到查找结束总时间：" + stwtotal.Elapsed.TotalMilliseconds + "ms");
             }
             Console.ReadKey();
         }

测试结论：Dictionary<T,T>明显优于Hashtable

截图如下:

1.Hashtable

2Dictionary<int,string>

3,Dictionary<int,CityInfo>