title: create index on XML file
body: <p>I have an XML file <br>
  perhaps i usually do more than 100 query every minute with C# and XMLDatareader, that's why i am thinking to add an Index on it, is it possible? or Indexes are allowed only on DB like sqlserver/mysql?<br>
  thanks
  <br>
   Here my XML file, with the first record:</p>
  
  <pre><code> &lt;?xml version="1.0" standalone="yes"?&gt;
  &lt;NewDataSet&gt;
    &lt;xs:schema id="NewDataSet" xmlns="" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata"&gt;
      &lt;xs:element name="NewDataSet" msdata:IsDataSet="true" msdata:UseCurrentLocale="true"&gt;
        &lt;xs:complexType&gt;
          &lt;xs:choice minOccurs="0" maxOccurs="unbounded"&gt;
            &lt;xs:element name="Traduzioni"&gt;
              &lt;xs:complexType&gt;
                &lt;xs:sequence&gt;
                  &lt;xs:element name="Path" type="xs:string" /&gt;
                  &lt;xs:element name="IT" type="xs:string" minOccurs="0" /&gt;
                  &lt;xs:element name="EN" type="xs:string" minOccurs="0" /&gt;
                  &lt;xs:element name="FR" type="xs:string" minOccurs="0" /&gt;
                  &lt;xs:element name="PT" type="xs:string" minOccurs="0" /&gt;
                &lt;/xs:sequence&gt;
              &lt;/xs:complexType&gt;
            &lt;/xs:element&gt;
            &lt;xs:element name="extension_ref"&gt;
              &lt;xs:complexType&gt;
                &lt;xs:sequence&gt;
                  &lt;xs:element name="idKey" type="xs:string" minOccurs="0" /&gt;
                  &lt;xs:element name="Reference" type="xs:string" minOccurs="0" /&gt;
                  &lt;xs:element name="Ordine" type="xs:string" minOccurs="0" /&gt;
                  &lt;xs:element name="Dizione_EN" type="xs:string" minOccurs="0" /&gt;
                  &lt;xs:element name="Dizione_IT" type="xs:string" minOccurs="0" /&gt;
                  &lt;xs:element name="Dizione_PT" type="xs:string" minOccurs="0" /&gt;
                  &lt;xs:element name="Dizione_FR" type="xs:string" minOccurs="0" /&gt;
                  &lt;xs:element name="Dizione_SP" type="xs:string" minOccurs="0" /&gt;
                  &lt;xs:element name="idKey_old" type="xs:string" minOccurs="0" /&gt;
                &lt;/xs:sequence&gt;
              &lt;/xs:complexType&gt;
            &lt;/xs:element&gt;
          &lt;/xs:choice&gt;
        &lt;/xs:complexType&gt;
        &lt;xs:unique name="Constraint1" msdata:PrimaryKey="true"&gt;
          &lt;xs:selector xpath=".//Traduzioni" /&gt;
          &lt;xs:field xpath="Path" /&gt;
        &lt;/xs:unique&gt;
      &lt;/xs:element&gt;
    &lt;/xs:schema&gt;
  
    &lt;Traduzioni&gt;
      &lt;Path&gt;N.Ordine&lt;/Path&gt;
      &lt;IT&gt;N.Ordine&lt;/IT&gt;
      &lt;EN&gt;Order number&lt;/EN&gt;
      &lt;FR&gt;Numéro de commande&lt;/FR&gt;
      &lt;PT&gt;No de ordem:&lt;/PT&gt;
    &lt;/Traduzioni&gt;  
  </code></pre>