解决 EF where<T>(func) 查询的一个性能问题

前两年帮朋友 做了个网吧管理软件,采用动软的三层架构 sql语句生成的。最近因功能变更 要改动,而我这段正在做asp.net mvc +ef+autofac的一个电商网站。索性 就把原来的底层全重新了套用了我现在的架构 EF6.0+autofac+三层架构,上层的asp.net没有变。改完后发现交班页面打开巨慢。

   

跟踪EF生成的sql语句   发现生成的sql 有问题,查找的全表,而全表有近10万条的数据。

继续跟踪数据库的耗时查询 发现确实是这条语句占时间

为什么会这样呢,我在查询里做条件搜索了,为啥 结果不对呢?

贴出 BaseRepository.cs 的代码

 1 public class BaseRepository<T> :IDBbase<T>  where T : class
 2     {
 3         //实例化EF框架
 4        protected skdbContext db = new skdbContext();
 5 
 6         //添加
 7         public T AddEntities(T entity)
 8         {
 9             db.Entry<T>(entity).State = EntityState.Added;
10             db.SaveChanges();
11             return entity;
12         }
13 
14         //修改
15         public bool UpdateEntity(T entity)
16         {
17             db.Set<T>().Attach(entity);
18             db.Entry<T>(entity).State = EntityState.Modified;
19             return db.SaveChanges() > 0;
20         }
21 
22         //修改
23         public bool DeleteEntities(T entity)
24         {
25             db.Set<T>().Attach(entity);
26             db.Entry<T>(entity).State = EntityState.Deleted;
27             return db.SaveChanges() > 0;
28         }
29 
30         //查询
31         public IQueryable<T> LoadEntities(Func<T, bool> wherelambda)
32         {
33             return db.Set<T>().Where<T>(wherelambda).AsQueryable();
34         }
35         //查询单个
36         public T LoadEntitie(Func<T, bool> wherelambda)
37         {
38             return db.Set<T>().FirstOrDefault<T>(wherelambda);
39         }
40 
41         //分页
42         public IQueryable<T> LoadPagerEntities<S>(int pageSize, int pageIndex, out int total,
43             Func<T, bool> whereLambda, bool isAsc, Func<T, S> orderByLambda)
44         {
45             var tempData = db.Set<T>().Where<T>(whereLambda);
46 
47             total = tempData.Count();
48 
49             //排序获取当前页的数据
50             if (isAsc)
51             {
52                 tempData = tempData.OrderBy<T, S>(orderByLambda).
53                       Skip<T>(pageSize * (pageIndex - 1)).
54                       Take<T>(pageSize).AsQueryable();
55             }
56             else
57             {
58                 tempData = tempData.OrderByDescending<T, S>(orderByLambda).
59                      Skip<T>(pageSize * (pageIndex - 1)).
60                      Take<T>(pageSize).AsQueryable();
61             }
62             return tempData.AsQueryable();
63         }
64     }
View Code

调用代码 

return jiaobanitem.LoadEntities(t => t.JiaoBanID == jiaobanID && t.GoodsID == GoodsID).FirstOrDefault();

参考 nopCommerce  修改baserepository

  1 public class EFRepository<T> : IRepository<T> where T : class 
  2     {
  3         //实例化EF框架
  4        //protected YaFeiNetContext db = new YaFeiNetContext();
  5        private DbContext _context;
  6        private IDbSet<T> _entities;
  7 
  8        public EFRepository(DbContext context)
  9        {
 10            this._context = context;
 11        }
 12 
 13 
 14         //添加
 15         public virtual T AddEntities(T entity)
 16         {
 17             try
 18             {
 19                 if(entity==null)
 20                     throw new ArgumentNullException("entity");
 21                 
 22                 this.Entities.Add(entity);
 23                 this._context.SaveChanges();
 24                 return entity;
 25             }
 26             catch(DbEntityValidationException dbEx)
 27             {
 28                 var msg = string.Empty;
 29                 foreach(var validationErrors in dbEx.EntityValidationErrors)
 30                     foreach (var validationError in validationErrors.ValidationErrors)
 31                         msg += string.Format("Property:{0} Error:{1}", validationError.PropertyName, validationError.ErrorMessage) + Environment.NewLine ;
 32 
 33                 var fail = new Exception(msg,dbEx);
 34                 throw fail;
 35             }
 36         }
 37 
 38         //修改
 39         public virtual bool UpdateEntities(T entity)
 40         {
 41             try
 42             {
 43                 if (entity == null)
 44                     throw new ArgumentNullException("entity");
 45 
 46 
 47                // this.Entities.Attach(entity);
 48                // _context.Entry<T>(entity).State = EntityState.Modified;
 49                 return this._context.SaveChanges() > 0;
 50             }
 51             catch (DbEntityValidationException dbEx)
 52             {
 53                 var msg = string.Empty;
 54                 foreach (var validationErrors in dbEx.EntityValidationErrors)
 55                     foreach (var validationError in validationErrors.ValidationErrors)
 56                         msg += string.Format("Property:{0} Error:{1}", validationError.PropertyName, validationError.ErrorMessage) + Environment.NewLine;
 57 
 58                 var fail = new Exception(msg, dbEx);
 59                 throw fail;
 60             }
 61 
 62         }
 63 
 64         //修改
 65         public virtual bool DeleteEntities(T entity)
 66         {
 67             try
 68             {
 69                 if (entity == null)
 70                     throw new ArgumentNullException("entity");
 71 
 72                 //db2.Set<T>().Attach(entity);
 73                 //db2.Entry<T>(entity).State = EntityState.Deleted;
 74                 this.Entities.Remove(entity);
 75                 return this._context.SaveChanges() > 0;
 76             }
 77             catch (DbEntityValidationException dbEx)
 78             {
 79                 var msg = string.Empty;
 80                 foreach (var validationErrors in dbEx.EntityValidationErrors)
 81                     foreach (var validationError in validationErrors.ValidationErrors)
 82                         msg += string.Format("Property:{0} Error:{1}", validationError.PropertyName, validationError.ErrorMessage) + Environment.NewLine;
 83 
 84                 var fail = new Exception(msg, dbEx);
 85                 throw fail;
 86             }
 87 
 88 
 89         }
 90 
 91         //查询
 92         public virtual IQueryable<T> LoadEntities(Func<T, bool> wherelambda)
 93         {
 94             return this.Entities.Where<T>(wherelambda).AsQueryable();
 95         }
 96         //查询单个
 97         public virtual T LoadEntitie(Func<T, bool> wherelambda)
 98         {
 99             return this.Table.Where(wherelambda).FirstOrDefault();
100         }
101        /// <summary>
102        /// 根据主键查找
103        /// </summary>
104        /// <param name="id"></param>
105        /// <returns></returns>
106         public virtual T GetById(object id)
107         {
108             return this.Entities.Find(id);
109         }
110 
111 
112 
113 
114         //分页
115         public virtual IQueryable<T> LoadPagerEntities<S>(int pageSize, int pageIndex, out int total,
116             Func<T, bool> whereLambda, bool isAsc, Func<T, S> orderByLambda)
117         {
118 
119             var tempData = this.Entities.Where<T>(whereLambda);
120 
121                 total = tempData.Count();
122 
123                 //排序获取当前页的数据
124                 if (isAsc)
125                 {
126                     tempData = tempData.OrderBy<T, S>(orderByLambda).
127                           Skip<T>(pageSize * (pageIndex - 1)).
128                           Take<T>(pageSize).AsQueryable();
129                 }
130                 else
131                 {
132                     tempData = tempData.OrderByDescending<T, S>(orderByLambda).
133                          Skip<T>(pageSize * (pageIndex - 1)).
134                          Take<T>(pageSize).AsQueryable();
135                 }
136                 return tempData.AsQueryable();
137             
138 
139         
140         }
141 
142         protected virtual IDbSet<T> Entities
143         {
144             get
145             {
146                 if (_entities == null)
147                     _entities = _context.Set<T>();
148                 return _entities;
149             }
150         }
151 
152 
153         public virtual IQueryable<T> Table
154         {
155             get { return this.Entities; }
156         }
157 
158 
159     }
View Code

同时修改调用代码 为

return jiaobanitem.Table.Where(t=>t.JiaoBanID ==jiaobanID && t.GoodsID ==GoodsID).FirstOrDefault();

问题解决 页面响应不到100ms   同时调试中 生成的sql语句已经有 查询条件了

问题出在  

//查询
public IQueryable<T> LoadEntities(Func<T, bool> wherelambda)
{
  return db.Set<T>().Where<T>(wherelambda).AsQueryable();
}

为了验证,我在前台直接调用 

return this.context.Set<tb_e_jiaoBanItem>().Where(t => t.JiaoBanID == jiaobanID && t.GoodsID == GoodsID).AsQueryable().FirstOrDefault();

页面响应也是 100ms左右,性能没问题。直接调用 dbcontext的set<>方法 没问题。但跨了几层传递后 就有问题。并没有生成我想要的查询语句。

 

这个问题原来别人也碰到过  http://www.cnblogs.com/yjmyzz/archive/2008/09/06/1285564.html

如果传入Where的参数为Expression,则L2S会自动帮忙处理Expression的拼接;而如果传入的是Func,而L2S无法拼接Expression与Func,所以只好先把数据全部取出来,然后再应用Func来进行数据过滤。

代码应该修改为:

public virtual IEnumerable<T> LoadEntities(System.Linq.Expressions.Expression<Func<T,bool>> wherelambda)
{
return this.Table.Where<T>(wherelambda);
}

 

posted @ 2014-08-09 18:11  未煮熟的虾  阅读(2812)  评论(4编辑  收藏  举报