Question

I am using PHP and SimpleXML and was wondering which will be faster and use less memory. I am not concerned with element vs attribute, but more on the perforance with PHP. There are 10 departments and 20 different categories. A file can belong to multiple departments and categories.

<file dep1="1" dep2="1" dep3="0" cat1="0" cat2="0" cat3="1" path="\path\to\file">
    file description
</file>

or

<file path="\path\to\file">
    <departments dep1="1" dep2="1" dep3="0" />
    <categories cat1="0" cat2="0" cat3="1" />
    <description>file description</description>
</file>

Answer 1

Performance will be pretty much equal. Attribute nodes and element nodes in a DOM are basically the same data structure, they are derived from the same base class, the will perform the same.

The point is more: What XML structure matches your data. That’s the one you should use.

I’d tend to use something like this, this feels most natural to me:

<file>
    <path>\path\to\file</path>
    <description>file description</description>
    <departments>
        <dep id="1" />
        <dep id="2" />
        <!-- the ones that are 0 are omitted -->
    </departments>
    <categories>
        <cat id="3" />
    </categories>
</file>