1 files changed, 80 insertions, 0 deletions
diff --git a/db/post_migrate/20200909161624_cleanup_group_import_states_with_null_user_id.rb b/db/post_migrate/20200909161624_cleanup_group_import_states_with_null_user_id.rb
new file mode 100644
index 00000000000..861d9e40e77
--- /dev/null
+++ b/db/post_migrate/20200909161624_cleanup_group_import_states_with_null_user_id.rb
@@ -0,0 +1,80 @@
+# frozen_string_literal: true
+
+class CleanupGroupImportStatesWithNullUserId < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  # With BATCH_SIZE=1000 and group_import_states.count=600 on GitLab.com
+  # - 1 iteration will be run
+  # - each batch requires on average ~2500ms
+  # - 600 rows require on average ~1500ms
+  # Expected total run time: ~2500ms
+  BATCH_SIZE = 1000
+
+  disable_ddl_transaction!
+
+  class User < ActiveRecord::Base
+    self.table_name = 'users'
+  end
+
+  class Namespace < ActiveRecord::Base
+    self.table_name = 'namespaces'
+
+    belongs_to :owner, class_name: 'CleanupGroupImportStatesWithNullUserId::User'
+  end
+
+  class Member < ActiveRecord::Base
+    self.table_name = 'members'
+    self.inheritance_column = :_type_disabled
+
+    belongs_to :user, class_name: 'CleanupGroupImportStatesWithNullUserId::User'
+  end
+
+  class Group < Namespace
+    OWNER = 50
+
+    self.inheritance_column = :_type_disabled
+
+    def default_owner
+      owners.first || parent&.default_owner || owner
+    end
+
+    def parent
+      Group.find_by_id(parent_id)
+    end
+
+    def owners
+      Member.where(type: 'GroupMember', source_type: 'Namespace', source_id: id, requested_at: nil, access_level: OWNER).map(&:user)
+    end
+  end
+
+  class GroupImportState < ActiveRecord::Base
+    include ::EachBatch
+
+    self.table_name = 'group_import_states'
+
+    belongs_to :group, class_name: 'CleanupGroupImportStatesWithNullUserId::Group'
+    belongs_to :user, class_name: 'CleanupGroupImportStatesWithNullUserId::User'
+  end
+
+  def up
+    User.reset_column_information
+    Namespace.reset_column_information
+    Member.reset_column_information
+    Group.reset_column_information
+    GroupImportState.reset_column_information
+
+    GroupImportState.each_batch(of: BATCH_SIZE) do |batch|
+      batch.each do |group_import_state|
+        owner_id = Group.find_by_id(group_import_state.group_id)&.default_owner&.id
+
+        group_import_state.update!(user_id: owner_id) if owner_id
+      end
+    end
+
+    GroupImportState.where('user_id IS NULL').delete_all
+  end
+
+  def down
+    # no-op : can't go back to `NULL` without first dropping the `NOT NULL` constraint
+  end
+end