+1 for anything which can improve performance of generating views, especially when importing large datasets.
Maybe it's just me, but CouchDB "feels" much slower than an RDBMS for this. That is, an RDBMS might limit you to only a couple of hundred inserts per second, but at least all your indexes are being built too. With CouchDB I can bulk-insert 600+ docs per second on an old laptop but the subsequent view generation takes far, far longer. CouchDB ought to have some advantages over the RDBMS: all the 'new' docs are contiguous on disk, and it can add to its btrees in bulk, rather than once per insert. However it has handicaps too, notably erlang->JSON->JS->JSON->erlang serialisation and the associated context switches. I only just started profiling this and I don't see anything obviously bad, but I have a real-world app which only manages to index 10 or 20 docs per sec (emitting an average of ~10 K/V pairs per doc), admittedly with a bit of regexp munging in the Javascript view code.
