CouchDB doesn't do joins, which can impose serious schema design changes depending on your application. map/reduce is done at index time. You wouldn't ever want

CouchDB doesn't do joins, which can impose serious schema design changes depending on your application. map/reduce is done at index time. You wouldn't ever want to do it on the fly. The base CouchDB also wasn't clustered last I looked (a year ago maybe?); you had to use BigCouch, which was an OSS contribution by Cloudant that lagged both Cloudant's own offering and CouchDB releases. It was supposed to get merged into head though so there's a good chance that actually happened while I wasn't looking. If you're just looking at CouchDB though and not Cloudant, it's not all that compelling (IMO). No clustering. No integrated search. No transactions. No joins. Pretty shallow server metrics in the dashboard. CouchDB doesn't even really have queries AFAIK. Just index scans.