The tag and url tables have had the ref_count column removed, so now the schema for importing the data no longer matches the available data dumps.
http://forums.musicbrainz.org/viewtopic.php?id=3281
http://chatlogs.musicbrainz.org/musicbrainz-devel/2011/2011-12/2011-12-18.html#T11-30-14-77566
http://chatlogs.musicbrainz.org/musicbrainz-devel/2011/2011-12/2011-12-29.html#T16-49-05-514716