一次LINQ性能研究

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[Obsolete]        public virtual string UpdateBySecondOld(string secondID, IEnumerable<string> firstIDs)        {            //Stopwatch sw = new Stopwatch();            //sw.Start();            TDataContext context = new TDataContext();            TEntity t = new TEntity();            var olds = context.GetTable<TEntity>().Where(t.SecondIDEquals(secondID));            context.GetTable<TEntity>().DeleteAllOnSubmit(olds);            List<TEntity> urList = new List<TEntity>();            foreach (string firstID in firstIDs)            {                TEntity ur = new TEntity();                ur.ID = Guid.NewGuid().ToString();                ur.FirstID = firstID;                ur.SecondID = secondID;                urList.Add(ur);            }            context.GetTable<TEntity>().InsertAllOnSubmit(urList);            context.SubmitChanges();            //sw.Stop();            //TimeSpan ts = sw.Elapsed;            return Constances.ErrorMassage.SUCCEED;        }        public virtual string UpdateBySecond(string secondID, IEnumerable<string> firstIDs)        {            //Stopwatch sw = new Stopwatch();            //sw.Start();            TDataContext context = new TDataContext();            TEntity t = new TEntity();            string sql = "delete from " + TableName + " where " + t.SecondIDName + "='" + secondID + "'";            string sqlInsert = "insert into  " + TableName + "(id," + t.FirstIDName + "," + t.SecondIDName + ") values({0},{1},{2})";            context.Connection.Open();            DbTransaction trans = context.Connection.BeginTransaction();            context.Transaction = trans;            try            {                context.ExecuteCommand(sql);                foreach (string firstID in firstIDs)                {                    string guid = Guid.NewGuid().ToString();                    context.ExecuteCommand(sqlInsert, guid, firstID, secondID);                }                context.Transaction.Commit();                //sw.Stop();                //TimeSpan ts = sw.Elapsed;                return Constances.ErrorMassage.SUCCEED;            }            catch            {                context.Transaction.Rollback();                return Constances.ErrorMassage.FAILED;            }        }

如上，UpdateBySecondOld為LINQ函數，UpdateBySecond後來用ADO.NET改寫的ADO.NET的函數。

分別傳入18個firstID，分別測試10次，結果如下：

次別ADO.NETLINQ10.0360.1920.0690.08830.0540.09240.0390.08350.0340.08860.0490.07670.0490.08380.0480.07790.0460.107100.0590.081平均0.04830.0965

可見，ADO.NET速度是LINQ的兩倍。

這主要是因為LINQ的更新，刪除，都不是直接的，而是先要獲取數據，這樣就降低了效率。

用LINQ查詢，因該差別不大。