For migration of immutable events, there's a good research paper[1] that outlines five strategies available: multiple versions; upcasting; lazy transformation;

For migration of immutable events, there's a good research paper[1] that outlines five strategies available: multiple versions; upcasting; lazy transformation; in-place transformation; copy and transformation. The last approach even allows you to rewrite events into an entirely new store. [1] The Dark Side of Event Sourcing: Managing Data Conversion http://files.movereem.nl/2017saner-eventsourcing.pdf http://files.movereem.nl/2017saner-eventsourcing.pdf