Postgresql vs Mnesia vs Couchdb

[G.S.]

Hello everyone,

Anyone ever ran a benchmark against these 3 dbs to see which ones scale
better to terabyte scale? Also, are there any well known projects in Erlang
that are similar to Dynamo?
Also, what does everyone suggest one uses for a db if one knows that that db
might grow to be huge, I've heard that mnesia does not scale that well.

Thanks,
-Gene