Squash migrations

[rowanmiller]

It would be good to have the ability to squash several migrations into a single file to help reduce the number of files in a project.

We probably want to keep track of the original list of migration names so that we can reason about this when targeting an existing database that the original migrations were applied to in their un-squashed form.

[popcatalin81]

@rowanmiller how will squash work? Merge Migrations into one or simply place them in a single file.

I think merging will be problematic when a target database has partial migrations but not all from a squash.

[bricelam]

@popcatalin81 I suspect at first, it will simpy concatenate all the operations together into one migration. In the future, it may try and simplify the operations (e.g. renaming A -> B -> C will become just A -> C)

Correct, "rewriting history" is always a bad idea. Before squashing, you'll have to revert all the migrations you want to squash, squash them, then re-apply the new one. You shouldn't do it if the migrations have been applied on any database other than your local one.

This operation would be useful while developing a new feature. You could add all the migrations locally you want, but before merging your feature, you could squash them all down into a single migration.

[TheMadKow]

👍 For this idea

[markusvt]

I just wanted to suggest that idea also.. the migrations folder gets quite large quite fast if the projects develops over time

[dario-hd]

I was wondering if removing them all and creating an "initial migration" would be a better approach. In the end this is what I did recently. Of course the "initial migration" should be executed only on database creation. This will not only reduce the number of files in the project but it will also speed up the initial database creation if you recreate it multiple times e.g. for development and testing purposes. What do you guys think? @rowanmiller @bricelam

[pgrm]

I'm puzzled that this issue is so inactive. How are others solving the issue of the ever growing Migrations folder?

Could there be at least some best practice described in the documentation @AndriySvyryd ?

[bricelam]

@pgrm I briefly mentioned a strategy in the Migrations docs I'm adding...