title: Updating documents with SOLR
body: <p>I have a community website with 20.000 members using everyday a search form to find other members. The results are sorted by the last connected members. I'd like to use Solr for my search (right now it's mysql) but I'd like to know first if it's good practice to update the document of every member who would login in order to change their login date and time ? There will be around 20.000 update of documents a day, I don't really know if it's too much updating and could alter performances ? Tank you for your help. </p>