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If I create a list of XElements from an XDocument, is this a new copy of the list of elements created in memory?

If I have XDocument

it loaded into memory from XDocument.Load

and then I make a LINQ-XML query on it, like this:

XDocument doc = XDocument.Load(@"C:/doc.xml");
var orders = doc.Root.Element("Envelope").Elements("Order");

Is there a copy in memory IEnumerable<XElement>

returned by the second line? Or is it just a background copy of the originalXDocument

What if I actually listed it by calling .ToList()

?

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3 answers


XDocument.Load

will read the entire dataset into memory.

Data queries return links to existing items. For example, check the original source for GetElement , which is the yield

existing nodes for the caller directly (by reference).



The main additional memory created when a document is requested will be the memory needed to implement the iterators themselves, which should be extremely small compared to the size of the document.

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Just a link.



You will need to use an operator new

to allocate memory to a new one List<XElement>

on the heap.

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Is there an in memory copy of IEnumerable returned by the second string? Or is it just a reference copy of the original XDocument

As others have pointed out, its the last one.

If you need a Deep Clone of an element, you can use the constructor XElement

:

var ordersCopy = doc.Root.Element("Envelope").Elements("Order").Select(element => new XElement(element);
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