Very long compile times for small changes

Questions & Help Questions
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11 
➜  cforum_ex git:(master) ✗ mix ecto.create
The database for Cforum.Repo has already been created
➜  cforum_ex git:(master) ✗ mix ecto.migrate

21:31:50.913 [info]  == Running 20181023062557 Cforum.Repo.Migrations.MakeTagsGlobal.change/0 forward

21:31:50.915 [info]  alter table tags
** (Postgrex.Error) ERROR 42P01 (undefined_table) relation "tags" does not exist

EDIT: didn’t read the previous message correctly, will check now with mix compile