读取XML文件“有时"很慢 [英] Reading XML files is 'sometimes' slow

问题描述

现在，在开始解释问题之前，我已经阅读了几篇有关读取大小超过1 GB的XML文件的问题的文章.那不是我的问题，所以我相信.

我有两个XML文件，两个文件的大小均为4MB，文件A的元素大约为10000，文件B的元素为1500.具体的元素大小不同.

现在非常奇怪的是，文件A只需使用DataSet.ReadXML读取一秒钟的时间，而文件B则需要两分钟以上的时间！

有人以前发现过这样的东西吗?我缺少明显的东西吗?

XML文件的结构因此是

Hi,

Now before I start explaining my issue, I have read a few articles about issues reading XML files over a GB in size. That is not my issue, or so I believe.

I have two XML files, both about 4MB in size, file A with roughly 10000 elements, file B with 1500. The specific elements are differing in size.

Now quite bizarrely file A takes a fraction of a second to be read using DataSet.ReadXML and yet file B takes over two minutes!

Any one found anything like this before? Am I missing something obvious?

The structure of the XML files is thus

<?xml version="1.0" standalone="yes"?>
<NewDataSet>
    Schema definition here
    <element>
        <id>1</id>
        <datafield1>xxxx</datafield1>
        <datafield2>xxxx</datafield2>
        ....
    </element>
    <element>
        ....
</NewDataSet>

如果我对元素"一词的使用不正确，我深表歉意，a，我是一位自学成才的C#编码器.

任何帮助将不胜感激

干杯

I apologise if my use of the term ''element'' is incorrect, alas I am a self-taught C# coder.

Any help is greatly appreciated

Cheers

推荐答案

尝试指定XmlReadMode，这样可以提高性能.

Try specifying XmlReadMode, this would increase performance.

myDS.ReadXml("C:\\Test\\input.xml", XmlReadMode.ReadSchema);

既然您说的是两个文件都大约4 MB，但是一个文件有10000个元素，而第二个文件有1500个元素，因此我认为结构是不同的，这可能导致读取多个表.

您可能想在调用ReadXml方法之前尝试调用BeginLoadData.

Hi,
Since you are saying both the files are around 4 MB, but one has 10000 elements whereas second has 1500 elements, I assume, the structure is different which might be causing multiple table reading.

You may like to try calling BeginLoadData before calling ReadXml method.

foreach (DataTable dataTable in dataSet.Tables)
   dataTable.BeginLoadData();

dataSet.ReadXml("file.xml"); 

foreach (DataTable dataTable in dataSet.Tables)
   dataTable.EndLoadData();

上述代码的更多详细信息和来源是MSDN，网址为 http://msdn.microsoft.com/en-us /library/fx29c3yd.aspx [ ^ ]

希望对您有帮助

-Milind

More details and source of the above code is MSDN at http://msdn.microsoft.com/en-us/library/fx29c3yd.aspx[^]

Hope that helps

- Milind

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