Store checksum of previous migration in each migration

[JanTvrdik]

The migrations:create command would instead of empty file create file with first line containing reference to parent migration, e.g. sth like

# parent = structures/2015-08-28-142150-init.sql/786340a54b68591563e983f60f82fecc

This will allow us to detect when programmer forgot to „rebase migrations“. This would also probably required some tool to help with the rebasing etc.

[hrach]

Great! I was thinking about similar solution of storing such thing into separate file... :)

[Mikulas]

👍 It would be handy to have a migrations:rebase tool then though, creating those headers manually after rebase would be huge pain.

Also it can't be integrated into old migrations easily as their checksum would change.

[hrach]

I have a different idea. What we want is the security, that prevent's us from merging pull request if it contains migrations which is not the last. Such check may be done by CI server that run your test suite on the merge commit. However, the current proposed solution does not solve this, if the test suite (and migraiton command) is not run on the merge, just on the head of branch (=current CircleCI's behavior).

My idea is the following:
store in some file the last migration name (or hash, but name is independent on the migrations contents and therefore no regeneration is needen, also, it's more explicit) and any pull-request would fail by merge conflict, if you try to merge migraiton which is not the last. Then, rebase on the master head would be needed.

What do you think?

[Mikulas]

That would work, but it could lead to false sense of security with git rerere enabled (it would resolve the conflict but keep the new migration not-rebased). Other than that I don't see a problem.