CouchDB: Intercepting Document Updates and Server-Side Processing
For the last couple of weeks, we’ve run a series of CouchDB Tips and I think that this one would be a nice addition to the list.
Starting with its version 0.10, CouchDB offers the possibility to perform server-side processing of incoming documents before they are committed. This feature is available through document update handlers defined in a design doc. You can find more details and a sample application of this feature on the linked page.