Solr indexing some of fields in a Tuple

I am new to Solr. I have a question regarding Solr indexing. Currently we have below configuration to index all the fields in a Tuple.

<!--contact fields -->
<field indexed="true" multiValued="false" name="contact" stored="false" type="TupleField"/>
<field docValues="true" indexed="true" multiValued="false" name="contact.first_name" stored="false" type="TextField"/>
<field docValues="true" indexed="true" multiValued="false" name="contact.last_name" stored="false" type="TextField"/>
<field docValues="true" indexed="true" multiValued="false" name="contact.email" stored="false" type="TextField"/>

I am trying to avoid indexing unwanted fields. In the above config i wanted to remove the indexing for first_name and last_name. Basically i want to have index on email field only.

Do i need to remove the fields (first_name and last_name) in the above config and mention

<field indexed="true" multiValued="false" name="contact" stored="false" type="TupleField"/>
<field docValues="true" indexed="true" multiValued="false" name="contact.email" stored="false" type="TextField"/>

or I need to mention all the fields and make docValues and indexed as false? I guess both are same. But can some one confirm above change is good?