: I did look into updatable docValues, but my understanding is that the : field has to be non-indexed (indexed="false"). I need to be able to sort : on these values. External field fields are sortable.
YOu can absolutely sort on a field that is docValues="true" indexed="false" ... that is much more efficient then sorting on a field that is docValues="false" index="true" -- in the later case solr has to build a fieldcache (aka: run-time-mock-docvalues) from the indexed values the first time you try to sort on the field after a searcher is opened -Hoss http://www.lucidworks.com/