[alextgordon]

I think I prefer the first version. At least the conflict is obvious.

Developer A creates migration 20100604181252. Developer B creates migration 20100604181253. Developer B doesn't notice Developer A's migration: there's no way to know from the timestamps that there might be a conflict. Everything breaks.

vs

Developer A creates migration 201. Developer B creates migration 201. Developer B gets a handy notification that something has happened in the meantime, and gets a chance to patch the migration if necessary.

[binbasti]

Actual conflicts from working with the same fields in the same tables are so rare, I haven't even experienced it once.

However, the second scenario would happen every single day in a team.

[tim_iles]

I have occasionally modified a sproc, only to find that a conflicting check-in has also modified that same sproc. One of our modifications has been overwritten by the other.

I do concede it is rare, but it happened, and we only discovered the bug too late.

[rahoulb]

The real issue is when you have feature branches and merge them in to master/trunk - so it's not a single file conflicting, but maybe a week or more's worth of work from both developers.

As you say, it would rely on notifications that there was the possibility of clashes, but unless you monitor every other developer's local feature branch, you would only know when the branches are merged into master.