Are you sure that the Solr Index Server of your production environment is updating your content?
As a consequence, are you sure that your Alfresco search indexes are correctly (and regularly) updated?
From a theoretical point of view, the answer is ‘yes’, but in a real life scenario, something could goes wrong and a message in our email box could arrive from your users, saying:
Hei fellow, the Alfresco installation that you are maintaining cannot find the documents I have uploaded a lot of time ago: this is not acceptable!
In this post is described a project that has, as its main goal, to avoid this awful issue. The project is called Solr probe (solr-probe) ad it is available on GitHub, for Solr versions greater than 1.4 (the one used from a lot of Alfresco versions).