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:
1 /// <summary> 2 /// 城市信息 3 /// </summary> 4 public class CityInfo 5 { 6 public string CityName { get; set; } 7 public string ProvinceName { get; set; } 8 } 9 /// <summary> 10 /// 数据仓库和查找方法 11 /// </summary> 12 public static class Respository 13 { 14 15 16 public static Hashtable Retrieve() 17 { 18 Hashtable data = new Hashtable(); 19 for (int i = 0; i < 100000; i++) 20 { 21 data.Add(i+1,"data"+i); 22 } 23 return data; 24 } 25 public static string Find(Hashtable data,int id) 26 { 27 var query = from item in data.Cast<DictionaryEntry>() where (int)item.Key == id select item.Value.ToString(); 28 return query.First(); 29 } 30 31 32 public static Dictionary<int, string> SecondRetrieve() 33 34 { 35 Dictionary<int,string> data = new Dictionary<int,string>(); 36 for (int i = 0; i < 100000; i++) 37 { 38 data.Add(i + 1, "data" + i); 39 } 40 return data; 41 } 42 43 public static string SecondFind(Dictionary<int, string> data, int id) 44 { 45 var query = from item in data where (int)item.Key == id select item.Value; 46 return query.First(); 47 } 48 49 public static Dictionary<int, CityInfo> ThridRetrieve() 50 { 51 Dictionary<int, CityInfo> data = new Dictionary<int, CityInfo>(); 52 for (int i = 0; i < 100000; i++) 53 { 54 data.Add(i + 1, new CityInfo { CityName="CityName"+i, ProvinceName="ProvinceName"+i }); 55 } 56 return data; 57 } 58 59 public static CityInfo ThridFind(Dictionary<int, CityInfo> data, int id) 60 { 61 var query = from item in data where (int)item.Key == id select item.Value; 62 return query.First(); 63 } 64 }
测试入口:
1 static void Main(string[] args) 2 { 3 { 4 Stopwatch stwtotal = new Stopwatch(); 5 stwtotal.Start(); 6 Hashtable data = Respository.Retrieve(); 7 for (int i = 1; i < 20; i++) 8 { 9 Stopwatch stw = new Stopwatch(); 10 stw.Start(); 11 Random r = new Random(); 12 string result = Respository.Find(data, r.Next(1, 1000)*i); 13 stw.Stop(); 14 Console.WriteLine(result + " FirstFindExecuteTime:" + stw.Elapsed.TotalMilliseconds+"ms"); 15 } 16 stwtotal.Stop(); 17 Console.WriteLine("测试数据总时间：" + stwtotal.Elapsed.TotalMilliseconds + "ms"); 18 } 19 { 20 Stopwatch stwtotal = new Stopwatch(); 21 stwtotal.Start(); 22 Dictionary<int, string> data = Respository.SecondRetrieve(); 23 for (int i = 1; i < 20; i++) 24 { 25 Stopwatch stw = new Stopwatch(); 26 stw.Start(); 27 Random r = new Random(); 28 string result = Respository.SecondFind(data, r.Next(1, 1000)*i); 29 stw.Stop(); 30 Console.WriteLine(result + " SecondFindExecuteTime:" + stw.Elapsed.TotalMilliseconds+"ms"); 31 } 32 stwtotal.Stop(); 33 Console.WriteLine("测试数据总时间：" + stwtotal.Elapsed.TotalMilliseconds + "ms"); 34 } 35 { 36 Stopwatch stwtotal = new Stopwatch(); 37 stwtotal.Start(); 38 Dictionary<int, CityInfo> data = Respository.ThridRetrieve(); 39 for (int i = 1; i < 20; i++) 40 { 41 Stopwatch stw = new Stopwatch(); 42 stw.Start(); 43 Random r = new Random(); 44 CityInfo result = Respository.ThridFind(data, r.Next(1, 1000) * i); 45 stw.Stop(); 46 Console.WriteLine(result.CityName + " ThridFindExecuteTime:" + stw.Elapsed.TotalMilliseconds + "ms"); 47 } 48 stwtotal.Stop(); 49 Console.WriteLine("真实数据初始化到查找结束总时间：" + stwtotal.Elapsed.TotalMilliseconds + "ms"); 50 } 51 Console.ReadKey(); 52 }
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>
