Hello, I suppose this is important to do if we ever want to move SLRUs into shared buffers. However, I wonder about the extra time this adds to pg_upgrade. Is this something we should be concerned about? Is there any measurement/estimates to tell us how long this would be? Right now, if you use a cloning strategy for the data files, the upgrade should be pretty quick ... but the amount of data in pg_xact and pg_multixact could be massive, and the rewrite is likely to take considerable time.
-- Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/ "Las cosas son buenas o malas segun las hace nuestra opinión" (Lisias)
