@mikem hesitating if we want to have faster migration or safer but blocking index creation.

I had the same fix in #4033

Having just the one thing outside the block (and after it) means that the only way the migration script can fail and still make changes is to fail on this index creation. We already have the if not exists clause, so it seems unlikely to fail in any reasonable scenario.

OTOH, I suppose the safest thing would be to make the default script transactional, but offer an alternative script with this optimization and document in the release notes.

Do we have a sense of how long this index creation will take for a large system? (granted I think all the large systems we deal with have already applied this index).

Breadcrumb: index comes from #4026

It is still relatively short. I've tried with ours and it is about ~1 minute.

If an instance as big as ours is just one minute, let's keep it all transactional

https://pagure.io/fork/mikem/koji/commits/pr4081updates

@tkopecek does my update here look ok? If so, want to pull in? Or should I file a different PR?

Let's create a new one. There are also some conflicts with current master.

Ok, filed #4141