Sorry in advance of this isn’t helpful - We’ve done it successfully a few times since 1.11… but not without a sacrifice of the virgins-in-volcano variety. Just about any kind of RunPython command seems to get in the way. And sometimes it’s easier to blow them all away and create fresh migrations.
I have faith in migration squashing. It feels like more art than science, and to be sure - dealing with a database is more art than science in general… especially with all the creative minds that have access to such a logical system. I believe squashing should be used with care, and mostly on systems with ideal schema. Aside of that, I’ve worked on projects with migrations in the several-hundreds which took long enough to stand up that I could get a coffee and continue working. All that said, I think it’s a nice-to-have feature, but ultimately isn’t necessary for the vast majority of projects. Benny > On May 11, 2021, at 7:50 PM, 'Mike Lissner' via Django developers > (Contributions to Django itself) <django-developers@googlegroups.com> wrote: > > I have a pretty big django project, and since I created the 100th migration > within one of its apps today, I thought I'd finally do some squashing. It > hasn't gone well, but I eventually got the data migrations cleaned up. > > Finally, I run it, and it runs smack into a CircularDependencyError, as > described here: > > https://code.djangoproject.com/ticket/23337 > > Basically, from what I understand, after the squash you have one migration > that depends on various others from your other apps. Naturally, that totally > falls over, because can't go from this series of migrations: > > app1: migration 1 > app2: migration 1 > app2: migration 2 > app1: migration 2 > > To, well...any series of migrations in which migration 1&2 from app1 or app2 > have been squashed. The docs have something to say about this*, but it feels > like this must affect practically any biggish project. > > Stackoverflow also has a variety of dubious (and very complex) advice (read > it and weep): > > https://stackoverflow.com/questions/37711402/circular-dependency-when-squashing-django-migrations > > So, my question is: Do people actually use squashmigrations with success? And > if not, is it reasonable to consider deprecating it or fixing the bug, or > updating the docs to loudly say it largely doesn't work? I'm surprised the > issue above has so little movement since it was created seven years ago. > > Maybe it's just me? If not, it'd be nice to do something to help future > people with ambitions of a simple squash. > > Thanks, > > > Mike > > * Note that model interdependencies in Django can get very complex, and > squashing may result in migrations that do not run; either mis-optimized (in > which case you can try again with --no-optimize, though you should also > report an issue), or with a CircularDependencyError, in which case you can > manually resolve it. > To manually resolve a CircularDependencyError, break out one of the > ForeignKeys in the circular dependency loop into a separate migration, and > move the dependency on the other app with it. If you’re unsure, see how > makemigrations deals with the problem when asked to create brand new > migrations from your models. In a future release of Django, squashmigrations > will be updated to attempt to resolve these errors itself. [Author's note: > These sentences really leave me blowing in the wind...maybe I can figure out > what they mean, I guess? I thought squashing was supposed to be easy.] > > > > -- > You received this message because you are subscribed to the Google Groups > "Django developers (Contributions to Django itself)" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to django-developers+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-developers/87f449bc-d653-427a-ac28-879ee0701c8bn%40googlegroups.com. -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-developers+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/E949F021-480A-40C3-9C98-2B1BDE95C368%40twosensedesign.com.
