diff --git a/changelogs/unreleased/36631-activerecord-statementinvalid-pg-querycanceled-error-canceling-statement-due-to-statement-timeout.yml b/changelogs/unreleased/36631-activerecord-statementinvalid-pg-querycanceled-error-canceling-statement-due-to-statement-timeout.yml
new file mode 100644
index 00000000000..a2e1d07158b
--- /dev/null
+++ b/changelogs/unreleased/36631-activerecord-statementinvalid-pg-querycanceled-error-canceling-statement-due-to-statement-timeout.yml
@@ -0,0 +1,6 @@
+---
+title: Reschedule merge request diff background migrations to catch failures from
+  9.5 run
+merge_request:
+author:
+type: fixed
diff --git a/db/post_migrate/20170926150348_schedule_merge_request_diff_migrations_take_two.rb b/db/post_migrate/20170926150348_schedule_merge_request_diff_migrations_take_two.rb
new file mode 100644
index 00000000000..5732cb85ea5
--- /dev/null
+++ b/db/post_migrate/20170926150348_schedule_merge_request_diff_migrations_take_two.rb
@@ -0,0 +1,32 @@
+class ScheduleMergeRequestDiffMigrationsTakeTwo < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  BATCH_SIZE = 500
+  MIGRATION = 'DeserializeMergeRequestDiffsAndCommits'
+  DELAY_INTERVAL = 10.minutes
+
+  disable_ddl_transaction!
+
+  class MergeRequestDiff < ActiveRecord::Base
+    self.table_name = 'merge_request_diffs'
+
+    include ::EachBatch
+
+    default_scope { where('st_commits IS NOT NULL OR st_diffs IS NOT NULL') }
+  end
+
+  # By this point, we assume ScheduleMergeRequestDiffMigrations - the first
+  # version of this - has already run. On GitLab.com, we have ~220k un-migrated
+  # rows, but these rows will, in general, take a long time.
+  #
+  # With a gap of 10 minutes per batch, and 500 rows per batch, these migrations
+  # are scheduled over 220_000 / 500 / 6 ~= 74 hours, which is a little over
+  # three days.
+  def up
+    queue_background_migration_jobs_by_range_at_intervals(MergeRequestDiff, MIGRATION, DELAY_INTERVAL, batch_size: BATCH_SIZE)
+  end
+
+  def down
+  end
+end
diff --git a/spec/migrations/schedule_merge_request_diff_migrations_take_two_spec.rb b/spec/migrations/schedule_merge_request_diff_migrations_take_two_spec.rb
new file mode 100644
index 00000000000..4ab1bb67058
--- /dev/null
+++ b/spec/migrations/schedule_merge_request_diff_migrations_take_two_spec.rb
@@ -0,0 +1,59 @@
+require 'spec_helper'
+require Rails.root.join('db', 'post_migrate', '20170926150348_schedule_merge_request_diff_migrations_take_two')
+
+describe ScheduleMergeRequestDiffMigrationsTakeTwo, :migration, :sidekiq do
+  matcher :be_scheduled_migration do |time, *expected|
+    match do |migration|
+      BackgroundMigrationWorker.jobs.any? do |job|
+        job['args'] == [migration, expected] &&
+          job['at'].to_i == time.to_i
+      end
+    end
+
+    failure_message do |migration|
+      "Migration `#{migration}` with args `#{expected.inspect}` not scheduled!"
+    end
+  end
+
+  let(:merge_request_diffs) { table(:merge_request_diffs) }
+  let(:merge_requests) { table(:merge_requests) }
+  let(:projects) { table(:projects) }
+
+  before do
+    stub_const("#{described_class.name}::BATCH_SIZE", 1)
+
+    projects.create!(id: 1, name: 'gitlab', path: 'gitlab')
+
+    merge_requests.create!(id: 1, target_project_id: 1, source_project_id: 1, target_branch: 'feature', source_branch: 'master')
+
+    merge_request_diffs.create!(id: 1, merge_request_id: 1, st_commits: YAML.dump([]), st_diffs: nil)
+    merge_request_diffs.create!(id: 2, merge_request_id: 1, st_commits: nil, st_diffs: YAML.dump([]))
+    merge_request_diffs.create!(id: 3, merge_request_id: 1, st_commits: nil, st_diffs: nil)
+    merge_request_diffs.create!(id: 4, merge_request_id: 1, st_commits: YAML.dump([]), st_diffs: YAML.dump([]))
+  end
+
+  it 'correctly schedules background migrations' do
+    Sidekiq::Testing.fake! do
+      Timecop.freeze do
+        migrate!
+
+        expect(described_class::MIGRATION).to be_scheduled_migration(10.minutes.from_now, 1, 1)
+        expect(described_class::MIGRATION).to be_scheduled_migration(20.minutes.from_now, 2, 2)
+        expect(described_class::MIGRATION).to be_scheduled_migration(30.minutes.from_now, 4, 4)
+        expect(BackgroundMigrationWorker.jobs.size).to eq 3
+      end
+    end
+  end
+
+  it 'migrates the data' do
+    Sidekiq::Testing.inline! do
+      non_empty = 'st_commits IS NOT NULL OR st_diffs IS NOT NULL'
+
+      expect(merge_request_diffs.where(non_empty).count).to eq 3
+
+      migrate!
+
+      expect(merge_request_diffs.where(non_empty).count).to eq 0
+    end
+  end
+end