For something like ConstantScoreRangeQuery, or a query that scores based on field contents, it doesn't make sense to have an idf() (and hence I leave it out).
However, I'm worried about how these constant scores will vary with respect to other clauses when the index changes size. Does it make sense to use a constant like idf(1) when scoring these queries in an attempt to keep the weights in proportion? -Yonik
