I want to tune the relevance of solr search results on a per user basis - based on the number of times the user has clicked through a result before. Frequently hit items FOR THAT USER should rise to the top of their search results.

Is there a way to provide custom boost/elevation for particular document ids on the query? I'm thinking in the order of ~100s of particular documents to elevate. The elevation should have no effect if the rest of the query doesn't find those documents.

Alternatively, if this isn't possible, what is a sane way for setting up an alternative indexing approach that would make this possible? Could I add a field per user in the index to store their scores? I'm thinking in the order of 1000 users. The major drawback of that approach is the number of times a document would need to be reindexed (i.e. each time it was used by the user).