I'm reading through this post: Demystifying Workflow History (Part 1) and I see that there are two locations that store a workflow's history, the default/hidden NintexWorkflowHistory list in the SharePoint content DB and the Nintext DB (WorkflowProgress table).
My question is this: If I purge the list items from the NintexWorkflowHistory list, does this also affect the ability to review the Nintex Workflow History on the Workflow Details page within SharePoint (via "View Workflow History" link on the item or the site actions menu)? In other words, does the Nintex details page source the Workflow history from the NintexWorkflowHistory list or from the database?
So the "View Workflow History" pulls only from the SharePoint NintexWorkflowHistory list (in the SharePoint content db)? The article makes it sound like it pulls data from the Nintex database.
Ah now I get your question. Sorry, didn't read carefully enough.
As you found out there are two places. Cleaning the workflow history list in SharePoint will not affect the Nintex history as the information is read from the database. However, everything under "workflow" and the history or everything accessed by workflow status column will become blank.