I was thinking it would be cool to be able to specify some number of most recent revisions to preserve during compaction. In some cases you only care about e.g. the two most recent revisions of a document, and don't care about the hundreds of older revisions that are just wasting space.
You could extend this idea by having compaction take an arbitrary predicate function operating on old revisions to determine which are retained, but maybe this needlessly complicates things. Thoughts?
