Migrate remaining users with null private_profile

changelogs/unreleased/post-migrate-private-profile.yml

+---
+title: Migrate remaining users with null private_profile
+merge_request: 31708
+author:
+type: other

db/post_migrate/20190812070645_migrate_private_profile_nulls.rb

+# frozen_string_literal: true
+
+class MigratePrivateProfileNulls < ActiveRecord::Migration[5.2]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  DELAY = 5.minutes.to_i
+  BATCH_SIZE = 1_000
+
+  disable_ddl_transaction!
+
+  class User < ActiveRecord::Base
+    self.table_name = 'users'
+
+    include ::EachBatch
+  end
+
+  def up
+    # Migration will take about 7 hours
+    User.where(private_profile: nil).each_batch(of: BATCH_SIZE) do |batch, index|
+      range = batch.pluck(Arel.sql("MIN(id)"), Arel.sql("MAX(id)")).first
+      delay = index * DELAY
+
+      BackgroundMigrationWorker.perform_in(delay.seconds, 'MigrateNullPrivateProfileToFalse', [*range])
+    end
+  end
+
+  def down
+    # noop
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
-ActiveRecord::Schema.define(version: 2019_08_06_071559) do
+ActiveRecord::Schema.define(version: 2019_08_12_070645) do
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_trgm"