1 files changed, 43 insertions, 0 deletions
diff --git a/db/post_migrate/20200806173633_migrate_null_package_files_file_store_to_local_value.rb b/db/post_migrate/20200806173633_migrate_null_package_files_file_store_to_local_value.rb
new file mode 100644
index 00000000000..088b85dd5da
--- /dev/null
+++ b/db/post_migrate/20200806173633_migrate_null_package_files_file_store_to_local_value.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+class MigrateNullPackageFilesFileStoreToLocalValue < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  JOB_INTERVAL = 2.minutes + 5.seconds
+  BATCH_SIZE = 5_000
+  MIGRATION = 'SetNullPackageFilesFileStoreToLocalValue'
+
+  disable_ddl_transaction!
+
+  class PackageFile < ActiveRecord::Base
+    self.table_name = 'packages_package_files'
+
+    include ::EachBatch
+  end
+
+  def up
+    # On GitLab.com, there are 2M package files. None have NULL file_store
+    # because they are all object stored. This is a no-op for GitLab.com.
+    #
+    # If a customer had 2M package files with NULL file_store, with batches of
+    # 5000 and a background migration job interval of 2m 5s, then 400 jobs would
+    # be scheduled over 14 hours.
+    #
+    # The index `index_packages_package_files_file_store_is_null` is
+    # expected to be used here and in the jobs.
+    #
+    # queue_background_migration_jobs_by_range_at_intervals is not used because
+    # it would enqueue 18.6K jobs and we have an index for getting these ranges.
+    PackageFile.where(file_store: nil).each_batch(of: BATCH_SIZE) do |batch, index|
+      range = batch.pluck(Arel.sql("MIN(id)"), Arel.sql("MAX(id)")).first
+      delay = index * JOB_INTERVAL
+
+      migrate_in(delay.seconds, MIGRATION, [*range])
+    end
+  end
+
+  def down
+    # noop
+  end
+end