Linq查询需要时间 [英] Linq query taking time

问题描述

任何人都可以建议我为什么我的linq查询需要时间

Can anyone please suggest me why my linq query taking time

lstSearch = (From s In lstGetResult
     Where (s.CODE.StartsWith(txtCode.Text.Trim(), StringComparison.OrdinalIgnoreCase)) OrElse
     (s.NAME.StartsWith(txtCode.Text.Trim(), StringComparison.OrdinalIgnoreCase))
     Select New SPGet_Result With {.CODE = s.CODE, .NAME = s.NAME}).ToList()

提前致谢：）

Thanks in advance :)

推荐答案

尝试拆分查询以找到最慢的部分。



注意：首先，我认为记住，很慢，可能是它包含甚至索引更快，结果是你搜索整个部分，而不是开始，所以撕裂ering可能会慢一点，如果你不想这样，你可以在你的txtCode和CODE / NAME的子串（0，长度）之间进行等于比较，并测试是否比statswith更快。

try to split the query to find the slowest part.

Note : the startswith, i think to remember, is quite slow, may be its faster a contains or even a indexof, the result is that you search the whole part, not the begining, so the rendering could be slower, if you don''t want that, you can make a "equals" comparison between your txtCode and a substring(0, length) of the CODE/NAME, and test if is faster than statswith.

var stopWatch = new System.Diagnostics.Stopwatch();
stopWatch.Start();

var tempLstSearch = lstGetResult;
var txtCode = txtCode.Text.Trim();

stopWatch.Stop();
var ts1 = stopWatch.Elapsed;

if(txtCode.Length > 0)
{
   tempLstSearch = tempLstSearch.Where(i=> (
                                             (i.CODE.IndexOf(txtCode,System.StringComparison.CurrentCultureIgnoreCase) >= 0) 
                                             ||
                                             (i.NAME.IndexOf(txtCode,System.StringComparison.CurrentCultureIgnoreCase) >= 0)
                                            ));
   stopWatch.Stop();
   var ts2 = stopWatch.Elapsed;
}

var search =  From s In tempLstSearch 
              Select New SPGet_Result With {.CODE = s.CODE, .NAME = s.NAME};

stopWatch.Stop();
varts3 = stopWatch.Elapsed;

var lstSearch = search.ToList()

stopWatch.Stop();
var ts4 = stopWatch.Elapsed;

lstSearch = (From s In lstGetResult
      Where (s.CODE.IndexOf(txtCode.Text.Trim(), StringComparison.OrdinalIgnoreCase) >= 0 OrElse
      s.NAME.IndexOf(txtCode.Text.Trim(), StringComparison.OrdinalIgnoreCase) >= 0)
      Select New SPGet_Result With
         {.CODE = s.CODE,.NAME = s.NAME}).ToList()

使用IndexOf及其转换工作更快



非常感谢katanakensei提示：）

Converted using IndexOf and its work more faster

many thanks "katanakensei" for hint :)

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