CouchDB doesn&#x27;t do joins, which can impose serious schema design changes depending on your application. map&#x2F;reduce is done at index time. You wouldn&#x27;t ever want to do it on the fly.<p>The base CouchDB also wasn&#x27;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&#x27;s own offering and CouchDB releases. It was supposed to get merged into head though so there&#x27;s a good chance that actually happened while I wasn&#x27;t looking.<p>If you&#x27;re just looking at CouchDB though and not Cloudant, it&#x27;s not all that compelling (IMO). No clustering. No integrated search. No transactions. No joins. Pretty shallow server metrics in the dashboard. CouchDB doesn&#x27;t even really have queries AFAIK. Just index scans.