I wouldn't use it for a write-heavy logging system ( and I am a big fan of it).

Well actually it depends on what type of logging. If you plan on pouring megabytes of data/sec second into it continuously you might want to find something else. I don't think CouchDB would be a good candidate for that. It might be if you plan on archiving your post-processed logged data for a long term storage but you have to be smart about its format.

Yeah 'logging' can mean a lot of things that it is hard to give a better advice without more information.

Other DBs/tools you might want to look at:

* rrdtool http://oss.oetiker.ch/rrdtool/

* MongoDB http://www.mongodb.org/

* Redis http://redis.io/

* Custom format + plain text files