We are in the process of upgrading a Sharepoint 2010 (with Nintex Workflow 2010) farm to Sharepoint 2013 (with Nintex Workflow 2013) and we need to know if the detach step on the Upgrade Guide (NW2010 - 2013 Upgrade Guide.pdf) is mandatory even if we are not using Nintex Live.
This is because we will do some "test migrations" before "prod migrations" and because we need a rollback plan.
Specifically for this apparently the detach process deletes workflow history according to Nintex WorkFlow 2010 - NWAdmin Operations.pdf
This operation detaches a content database from the environment. The detach process performs the following steps:
• Prepares any pending Live requests so they will not be processed in the current environment.
• Stores Live service information that will be required in the target environment.
• Unregisters the database from the environment and removes any site collection mappings that use it.
Running this command will cause workflow history to be lost from the environment. The command is intended to be run as part of the process of migrating a SharePoint database to another environment or in other scenarios where the data stored in it will no longer be required by the environment.