Alphanumeric field type for Solr which lowercases, removes leading articles, and forces numbers to sort numerically.

alphanumeric-field-type.xml

<fieldType name="alphaNumericSort" class="solr.TextField" sortMissingLast="false" omitNorms="true">
  <analyzer>
    <!-- KeywordTokenizer does no actual tokenizing, so the entire
         input string is preserved as a single token
      -->
    <tokenizer class="solr.KeywordTokenizerFactory"/>
    <!-- The LowerCase TokenFilter does what you expect, which can be
         when you want your sorting to be case insensitive
      -->
    <filter class="solr.LowerCaseFilterFactory" />
    <!-- The TrimFilter removes any leading or trailing whitespace -->
    <filter class="solr.TrimFilterFactory" />
    <!-- Remove leading articles -->
    <filter class="solr.PatternReplaceFilterFactory"
            pattern="^(a |the |les |la |le |l'|de la |du |des )" replacement="" replace="all"
    />
    <!-- Left-pad numbers with zeroes -->
    <filter class="solr.PatternReplaceFilterFactory"
            pattern="(\d+)" replacement="00000$1" replace="all"
    />
    <!-- Left-trim zeroes to produce 6 digit numbers -->
    <filter class="solr.PatternReplaceFilterFactory"
            pattern="0*([0-9]{6,})" replacement="$1" replace="all"
    />
    <!-- Remove all but alphanumeric characters -->
    <filter class="solr.PatternReplaceFilterFactory"
            pattern="([^a-z0-9])" replacement="" replace="all"
    />
  </analyzer>
</fieldType>