Couchbase Sync Gateway- Server and Client API vs bucket shadowing

Question

I am working on a project that uses Couchbase Server and Sync Gateway to synchronize the contents of a bucket with iOS and Android clients running Couchbase Lite. I also need read and write access to the Couchbase Server from a Node.js server application. From the research I've done, using shadowing is frowned upon (https://github.com/couchbase/sync_gateway/wiki/Bucket-Shadowing), which led me to look into the Sync Gateway API as a means to update the bucket from the Node.js application. Updating existing documents through the Sync Gateway API appears to require the most recent revision ID of the document to be passed in, requiring a separate read before the modification (http://mobile-couchbase.narkive.com/HT2kvBP0/cblite-sync-gateway-couchbase-server), which seems potentially inefficient. What is the best way to solve this problem?

Answer 1

Updating a document (which is really creating a new revision) requires the revision ID. Otherwise Couchbase can't associate the update with a parent. This breaks the whole approach to conflict resolution. (Couchbase uses a method known as multiversion concurrency control.)

The expectation is that you're updating the existing contents of a document. This implies you've read the document already, including the revision ID.

If for some reason you don't need to the old contents to update the document, you still need the revision ID. If you work around it (for example, by purging a document through Sync Gateway and then pushing your new version) you can end up with two versions of document in the system with no connection, which will cause a special kind of conflict.

So the short answer is no, there's no way to avoid this (without causing yourself other headaches).

Answer 2

I am not sure why your question was downvoted, as it seems like a reasonable question. You are correct, the Couchbase bucket that is used by Sync Gateway should probably best be thought of as "opaque", you should not be poking around in there and changing things. There are a number of implementations of Couchbase Lite, such as one for Java, .NET, and Mac OS X. Have you considered making a web service that, on one side, is serving your application, and on the other side is itself a Couchbase Lite client? You should be able to separate your data as necessary using channels.