I've been working tirelessly on this issue and have found no good solutions. I have two sets of polygon features, one containing 565,000 and the other containing 397,000 features. I've tried the following to execute a union:
Running a model in model builder (both in Arc and in Catalog)
Running a union in Arc
Running a model in FME
When I do any of the above, it either crashes or returns an empty feature class after reaching 100%. I looked into the empty feature class issue and the error code told me to change my extents to cover the whole feature class so I did, and it still won't work.
Does anyone have any experience with this or know of a better way to approach this?