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.NET Forum / .NET Framework / Compact Framework / January 2006XmlTextReader or XmlDocument or SQLCE
Hi. Im using DataSet.readXml/WriteXml for read/write data but is too slow (the size of my XML file is between 200,500ko) I want to use XMLTextWriter & Reader but i don't know if i can manipulate Data easily(read element,update element...) in My application I make a several calls to the XML file (update, read, insert elements) and I must save changes in XML file after each call.in this case what is the better and faster way to read/write data : XmlTexReader or XmlDocument or i must work with the SQL CE sorry for my bad English and Thank you for all your help Regards 200-500 kilobytes? if so then using any XML class in CF will be dog slow when XmlTextReader. SQL CE will improve performance no-end. I find just reading an XML config file in my app very slow and it is only around 300 bytes. Cheers Simon. > Hi. > [quoted text clipped - 10 lines] > > Regards Thanks for your help, but if I reduce the size of my XML file to 150 ko,200ko, I will have the same Problem? can I still work with XML file because SQl CE is not appropriate to me ? by using dataset functions the real problem is not in readxml function but in WriteXML because I must after each change of data call this function. that's mean if I update one record of dataset the function WriteXMl rewrite all the file. there is no possibility to save changes in XML file by another way for example by XMLTextWriter?instead of Dataset.writeXml? Regards Actually, this "dog slow" idea is mostly from combination of unrealistic expectations (e.g. my desktop with 3+GHz superscalar fully featured CPU with 2GB or extremely fast RAM does that in 1 seconds, why it takes 2 minutes on puny 200 MHz RISC processor with slow 16 bit 32 MB RAM?), older hardware (e.g. 100MHz PPC 2000), older versions of NETCF (V1 RTM instead of SP2+ or V2) and improper ways of working with XML (e.g. using inference to load XML into DataSet or using DOM to get a single value from a big file). It is very possible to achieve adequate performance on relatively modern hardware running NETCF V1 SP3 or V2. With XmlTextReader it should take about a second to read 200K document node by node. DataSet.ReadXml() would load it in about 2-3 seconds assuming schema is used. This data is for NETCF V2 running in PXA 255@400 MHz on PPC 2003. It's about twice as long for NETCF V1 SP3. So, it should be OK to use DataSet.ReadXml() with 200-500K XML. Just make sure: - You're using schema (typed DataSet, created programmatically, loaded from separate file or embedded into the XML). - Avoid using DateTime fields as they are very slow to parse. - Use related tables instead of nested tables. As to saving XML file after each change, simply don't do that. Imagine Word would save each time you type one character, now that would be terrible. DataSet is especially designed so you don't have to do that. It cashes data in memory so you can access and change it as needed and persist it from time to time. Save it only on user request, on timer or if your application closes. And no, there's no way to update part of XML with any class, it can only be rewritten as a whole. This is indeed a big disadvantage of XML compared to even comma separated file; you can at least add records to it which is not possible with XML. Best regards, Ilya This posting is provided "AS IS" with no warranties, and confers no rights. *** Want to find answers instantly? Here's how... *** 1. Go to http://groups-beta.google.com/group/microsoft.public.dotnet.framework.compactfra mework?hl=en 2. Type your question in the text box near "Search this group" button. 3. Hit "Search this group" button. 4. Read answer(s). > Thanks for your help, > [quoted text clipped - 10 lines] > > Regards I wouldn't really call it "unrealistic expectations", I would call it experience, and testing. I would love to see a 1 second response time reading a single node from a 200k XML file on any version of CF running on any processor. It's really a no brainer, why give yourself so much work when a tool such as SQL CE does it (and does it a lot better - with more options) without having to do hardly any work. > Actually, this "dog slow" idea is mostly from combination of unrealistic > expectations (e.g. my desktop with 3+GHz superscalar fully featured CPU [quoted text clipped - 73 lines] >> >> Regards Thanks for your help. I'm trying to test both of solutions :Dataset and SQL ce. about Dataset: I have installed SP2 and load a schema from seperate file xsd and Im not using DateTimeFields, so Dataset.readXML takes 7s instead of 28s for reading xml file with 200 Ko. but I dont understand how can I Use related tables instead of nested tables. I have one table who has a child table. Should I add PrimaryKey and foreing Key for those tables in the xsd file ? I have tried to do this but it generate an exception. I have already read an utility who reformat The Xml file buy modifing DataColumn.ColumnMapping to MappingType.Attribute. what should I do for using related table? Best Regards You should consider having primary key/foreign keys in any case; it's a must for any DB. As to relations, you can change relation type from nested to related in schema editor. Also, I've posted source code for utility which does that a while ago. Should be easy to find using link below. Best regards, Ilya This posting is provided "AS IS" with no warranties, and confers no rights. *** Want to find answers instantly? Here's how... *** 1. Go to http://groups-beta.google.com/group/microsoft.public.dotnet.framework.compactfra mework?hl=en 2. Type your question in the text box near "Search this group" button. 3. Hit "Search this group" button. 4. Read answer(s). > Thanks for your help. > [quoted text clipped - 11 lines] > > Best Regards Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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