Imagine you have Android & iOS apps which some of your users won't ever update. You'll never be able to drop any old version's tables, and you'll need to keep a

Imagine you have Android & iOS apps which some of your users won't ever update. You'll never be able to drop any old version's tables, and you'll need to keep all table versions in sync more or less in real-time. Only when the last user has updated from a certain client version will you be able to remove that version's tables.