Unique constraints in couchdb

Question

Are there any techniques/proposals to enforce unique constraints? Yes, we can create key that\'s unique, but we cannot change key and keys and also this approach is not suit

Answer 1

CouchDB has "changes feed" http://docs.couchdb.org/en/2.3.1/api/database/changes.html#changes

An update action is the same as a new action, only differing by _rev and object's 'new' property.

Filter functions work like a list or a show function but differ in being oriented to 'changes queue actions' http://docs.couchdb.org/en/2.3.1/ddocs/ddocs.html#filterfun

Design documents, contemplate the ability to filter any adding to the changes queue.

https://docs.couchdb.org/en/master/ddocs/index.html