With 0.2.x, it holds the whole database in memory while it builds the dmap tree. That’s the limit on 0.2.x — the size of the metadata.
With nightlies, it doesn’t hold anything in memory. It might be slow, because it has to do two database traversals to send the database information, but it shouldn’t be memory limited.
I can’t imagine that there are any memory limits on nightlies.
What version were you experiencing problems with?