Major upgrade: Upgrading Couchbase Server from 1.8 to 5.1


We are Planning to upgrade the current couchbase server. It is currently running version 1.8.1-937-rel. The plan is to upgrade to 5.1 version (Community Edition).

Details of the current server:

  1. Server version - 1.8.1-937-rel
  2. Bucket Type - Memcached
  3. Couchbase Java client version - 1.1.7

We are good with offline upgrade

Need help in these queries:

  1. I would like to know if there are any challenges in terms of code changes, performance, system requirements, etc.,
  2. Are we good with Memcached buckets or does it require upgrade to couchbase bucket?
  3. Will the java client needs upgrade too? i.e. to version 2.5.9?
  4. While upgrading the java client, will it require any API/code changes?

Any help would be greatly appreciated! Thanks!!