gov.uk did a good writeup of their 11 second migration of a 400gb database with ~1000 read/writes per second: https://gds.blog.gov.uk/2024/01/17/how-we-migrate

gov.uk did a good writeup of their 11 second migration of a 400gb database with ~1000 read/writes per second: https://gds.blog.gov.uk/2024/01/17/how-we-migrated-our-postgresql-database-with-11-seconds-downtime/ https://gds.blog.gov.uk/2024/01/17/how-we-migrated-our-postg... With their approach, there would always be a minimum of 1 second downtime from the DNS changeover.