We did this at low traffic sites too, even having "nights" at our disposal. Correctness is so nice – each code deploy happens calmly, no moving parts to coordinate ("hey okay code deploy now run the migration, quickly!!1")
How high traffic sites rename a db column without downtime.
1. Add new column
2. Double write to old/new column
3. Backfill new column
4. Switch reads/writes 100% to new column
5. Delete the old column
Each step is a code deploy
I can’t believe it’s been TWELVE years since @soveran and I committed the skeleton for the Redis website. It stood mostly unchanged until earlier this year. Thank you @antirez for writing such a beautiful piece of software and for letting us get involved <3
