I didn't mention that our DB setup uses sharding, and every tenant has their own DB shard (there are tens of thousands of shards). I just checked that one of th

I didn't mention that our DB setup uses sharding, and every tenant has their own DB shard (there are tens of thousands of shards). I just checked that one of the largest tenants has 2.2 mln rows in one of the affected tables, which is usually joined with 2-4 more related tables using UUIDs (another such table is 1.1 mln rows, for example), and they're on the hot code path because it's the core of the system. Maybe with sharding the difference is negligible? During code review I raised the concern that inserts and joins can become much slower after we migrate it to UUIDs, but so far my fears haven't materialized. Usually with these tables we have performance problems on the application side, not in the DB, such as ORM fetching data in a very inefficient way, or using too much RAM. Maybe it'll bite us in the long term as the tenants' shards grow in size, who knows.