When not to preserve DOM fidelity

Question

Does not preserving DOM fidelity helps performance in any way ?
What are the use cases where it makes sense to not preserve the DOM fidelity ?

Answer 1

Here's a complexType definition I have
      <xsd:complexType name="TextType" xdb:SQLType="MYC_TEXT_T">
            <xsd:simpleContent>
                  <xsd:extension base="xsd:string">
                        <xsd:attribute ref="xml:lang" xdb:SQLName="LANG" xdb:SQLType="VARCHAR2"/>
                  </xsd:extension>
            </xsd:simpleContent>
      </xsd:complexType>Notice that the LANG attribute is defined as a ref to "xml:lang", and for the xml name-space I also have in the beginning of my schema
<xsd:schema targetNamespace="http://www.mycompany.com/dictionary/2.0"
xmlns:mycompany="http://www.mycompany.com/dictionary/2.0" xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:xml="http://www.w3.org/XML/1998/namespace" elementFormDefault="qualified" attributeFormDefault="unqualified"
xmlns:xdb="http://xmlns.oracle.com/xdb" xdb:storeVarrayAsTable="true">
      <xsd:import namespace="http://www.w3.org/XML/1998/namespace" schemaLocation="http://www.w3.org/2001/xml.xsd"/>Now if I define the "TextType" Complex-type with xdb:maintainDOM="false", then the schema registers fine, but I cannot insert any data, I get the message ,
ERROR at line 1:
ORA-30937: No schema definition for 'lang' (namespace '##local') in parent
'/item-list/item[1]/title[1]'
ORA-06512: at line 6But I am able to successfully insert if I remove the maintainDOM=false from the TextType defn.
So looks like DOM fidelity is required if support for multiple name-spaces is required.