We've just had a Workflow History list hit 5000 items - yay people are using sharepoint!
A naive "Open Items" view filters on "Task Status" <> "Completed" and can be made to work with an index, but occasionally users like to complete tasks without setting an outcome! The tasks then drop off their views never to be seen again frustrating all abound.
Simple solution to this is to add a "OR "Task Outcome" not blank" condition to the view. Easy!
But this column doesn't even appear in the list of columns on the "create index" page. Am I out of luck?