1 files changed, 59 insertions, 0 deletions
diff --git a/db/post_migrate/20210901153324_slice_merge_request_diff_commit_migrations.rb b/db/post_migrate/20210901153324_slice_merge_request_diff_commit_migrations.rb
new file mode 100644
index 00000000000..8ee7feae1a6
--- /dev/null
+++ b/db/post_migrate/20210901153324_slice_merge_request_diff_commit_migrations.rb
@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+class SliceMergeRequestDiffCommitMigrations < ActiveRecord::Migration[6.1]
+  include Gitlab::Database::MigrationHelpers
+
+  disable_ddl_transaction!
+
+  BATCH_SIZE = 5_000
+  MIGRATION_CLASS = 'MigrateMergeRequestDiffCommitUsers'
+  STEAL_MIGRATION_CLASS = 'StealMigrateMergeRequestDiffCommitUsers'
+
+  def up
+    old_jobs = Gitlab::Database::BackgroundMigrationJob
+      .for_migration_class(MIGRATION_CLASS)
+      .pending
+      .to_a
+
+    return if old_jobs.empty?
+
+    transaction do
+      # This ensures we stop processing the old ranges, as the background
+      # migrations skip already processed jobs.
+      Gitlab::Database::BackgroundMigrationJob
+        .for_migration_class(MIGRATION_CLASS)
+        .pending
+        .update_all(status: :succeeded)
+
+      rows = []
+
+      old_jobs.each do |job|
+        min, max = job.arguments
+
+        while min < max
+          rows << {
+            class_name: MIGRATION_CLASS,
+            arguments: [min, min + BATCH_SIZE],
+            created_at: Time.now.utc,
+            updated_at: Time.now.utc
+          }
+
+          min += BATCH_SIZE
+        end
+      end
+
+      Gitlab::Database::BackgroundMigrationJob.insert_all!(rows)
+    end
+
+    job = Gitlab::Database::BackgroundMigrationJob
+      .for_migration_class(MIGRATION_CLASS)
+      .pending
+      .first
+
+    migrate_in(1.hour, STEAL_MIGRATION_CLASS, job.arguments)
+  end
+
+  def down
+    # no-op
+  end
+end