[jira] [Created] (COUCHDB-2396) Provide ?changes=true for all GET requests

["André Gaul (JIRA)" <ji...@apache.org>]

André Gaul created COUCHDB-2396:
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             Summary: Provide ?changes=true for all GET requests
                 Key: COUCHDB-2396
                 URL: https://issues.apache.org/jira/browse/COUCHDB-2396
             Project: CouchDB
          Issue Type: Wish
      Security Level: public (Regular issues)
          Components: HTTP Interface
            Reporter: André Gaul


h2. Situation

Assume you've made one of the following HTTP requests against a CouchDB:

* GET /albums/foobar
* GET /albums/_design/ddoc/_view/by_name?startkey=foo

In a lot of applications, you're interested in the changes that happened since the last request or you even want to receive continuous/live updates (e.g., via [Server Sent Events|http://www.w3.org/TR/eventsource/]). Actually, that's what CouchDB's _changes feed is made for (and it does a good job in a few projects I maintain). CouchDB 2.0 seems to go a step further by providing a changes feed for views (according to a discussion with [~janl] on irc, see also [here|https://github.com/rcouch/rcouch/wiki/View-Changes]). However, the _changes feed is a bit hard to use if you want to get the changes for a specific request with all involved parameters (e.g., for the above view query).

h2. Improvement

>From a user's perspective, it would be much simpler if the changes could be fetched for a specific request by simply appending _?changes=true_ and a _since_ parameter whose value was provided by the previous request, e.g. by

* GET /albums/foobar?changes=true&since=4711
* GET /albums/_design/ddoc/_view/by_name?startkey=foo&changes=true&since=4711

Technically, the changes reply could consist of [JSON patches|https://tools.ietf.org/html/rfc6902].

This kind of _changes_ feature would be great for all REST APIs in the context of (near-) real time apps. CouchDB probably has almost everything in place to support this feature and make life much easier ;). On the other hand, I can imagine that it requires a significant amount of work in CouchDB's internals.

Since I'm not too familiar with CouchDB's internals, I'd like to bring this idea up for discussion here.



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