This treats the entire text field as a single token. The kyword tokenizer is required in scenarios where we want to match the entire string as it is:

Factory class: solr.KeywordTokenizerFactory

Arguments: None

Example: 

<fieldType name="text_en" class="solr.TextField" positionIncrementGap="100">
 <analyzer>
 <tokenizer class="solr.KeywordTokenizerFactory"/>
 </analyzer>
</fieldType>

Input: Please send a mail at [email protected] by 12-Nov.

Output: Please send a mail at [email protected] by 12-Nov.

The entire input string is preserved as a single token.