Noop migrations containing faulty SQL regex

We had a mistake in our SQL regex, spotted by @a_akgun here:
  https://gitlab.com/gitlab-org/gitlab/-/merge_requests/67687#note_649843625

Changelog: fixed

db/migrate/20210816161107_remove_index_containing_faulty_regex.rb

+# frozen_string_literal: true
+
+class RemoveIndexContainingFaultyRegex < ActiveRecord::Migration[6.1]
+  include Gitlab::Database::MigrationHelpers
+
+  INDEX_NAME = "tmp_index_merge_requests_draft_and_status"
+
+  disable_ddl_transaction!
+
+  def up
+    remove_concurrent_index_by_name :merge_requests, INDEX_NAME
+  end
+
+  def down
+    # noop
+    #
+  end
+end

db/post_migrate/20210609202501_schedule_backfill_draft_status_on_merge_requests.rb

 # frozen_string_literal: true
 
 class ScheduleBackfillDraftStatusOnMergeRequests < ActiveRecord::Migration[6.1]
-  include Gitlab::Database::MigrationHelpers
-
-  INDEX_NAME = "tmp_index_merge_requests_draft_and_status"
-  MIGRATION = 'BackfillDraftStatusOnMergeRequests'
-  DELAY_INTERVAL = 2.minutes
-  BATCH_SIZE = 100
-
-  disable_ddl_transaction!
-
   def up
-    add_concurrent_index :merge_requests, :id,
-      where: "draft = false AND state_id = 1 AND ((title)::text ~* '^\\[draft\\]|\\(draft\\)|draft:|draft|\\[WIP\\]|WIP:|WIP'::text)",
-      name: INDEX_NAME
-
-    eligible_mrs = Gitlab::BackgroundMigration::BackfillDraftStatusOnMergeRequests::MergeRequest.eligible
-
-    queue_background_migration_jobs_by_range_at_intervals(
-      eligible_mrs,
-      MIGRATION,
-      DELAY_INTERVAL,
-      track_jobs: true,
-      batch_size: BATCH_SIZE
-    )
+    # noop
+    #
   end
 
   def down
-    remove_concurrent_index_by_name :merge_requests, INDEX_NAME
+    # noop
+    #
   end
 end

db/post_migrate/20210806011811_schedule_backfill_draft_column_on_merge_requests_rerun.rb

 # frozen_string_literal: true
 
 class ScheduleBackfillDraftColumnOnMergeRequestsRerun < ActiveRecord::Migration[6.1]
-  include Gitlab::Database::MigrationHelpers
-
-  MIGRATION = 'BackfillDraftStatusOnMergeRequests'
-  DELAY_INTERVAL = 2.minutes
-  BATCH_SIZE = 50
-
-  disable_ddl_transaction!
-
   def up
-    eligible_mrs = Gitlab::BackgroundMigration::BackfillDraftStatusOnMergeRequests::MergeRequest.eligible
-
-    queue_background_migration_jobs_by_range_at_intervals(
-      eligible_mrs,
-      MIGRATION,
-      DELAY_INTERVAL,
-      track_jobs: true,
-      batch_size: BATCH_SIZE
-    )
+    # noop
+    #
   end
 
   def down

db/schema_migrations/20210816161107

+1e4d0b062c8e43b1af37c6cf869f9c173248d7bf5451b4aa5468d48c1004b97c
\ No newline at end of file

db/structure.sql

@@ -25689,8 +25689,6 @@ CREATE INDEX tmp_idx_on_namespaces_delayed_project_removal ON namespaces USING b
 
 CREATE INDEX tmp_index_approval_project_rules_scanners ON approval_project_rules USING gin (scanners) WHERE (scanners @> '{cluster_image_scanning}'::text[]);
 
-CREATE INDEX tmp_index_merge_requests_draft_and_status ON merge_requests USING btree (id) WHERE ((draft = false) AND (state_id = 1) AND ((title)::text ~* '^\[draft\]|\(draft\)|draft:|draft|\[WIP\]|WIP:|WIP'::text));
-
 CREATE INDEX tmp_index_namespaces_empty_traversal_ids_with_child_namespaces ON namespaces USING btree (id) WHERE ((parent_id IS NOT NULL) AND (traversal_ids = '{}'::integer[]));
 
 CREATE INDEX tmp_index_namespaces_empty_traversal_ids_with_root_namespaces ON namespaces USING btree (id) WHERE ((parent_id IS NULL) AND (traversal_ids = '{}'::integer[]));

spec/migrations/schedule_backfill_draft_status_on_merge_requests_spec.rb

-# frozen_string_literal: true
-
-require 'spec_helper'
-
-require_migration!
-
-RSpec.describe ScheduleBackfillDraftStatusOnMergeRequests, :sidekiq do
-  let(:namespaces)     { table(:namespaces) }
-  let(:projects)       { table(:projects) }
-  let(:merge_requests) { table(:merge_requests) }
-
-  let(:group)   { namespaces.create!(name: 'gitlab', path: 'gitlab') }
-  let(:project) { projects.create!(namespace_id: group.id) }
-
-  let(:draft_prefixes) { ["[Draft]", "(Draft)", "Draft:", "Draft", "[WIP]", "WIP:", "WIP"] }
-
-  def create_merge_request(params)
-    common_params = {
-      target_project_id: project.id,
-      target_branch: 'feature1',
-      source_branch: 'master'
-    }
-
-    merge_requests.create!(common_params.merge(params))
-  end
-
-  before do
-    draft_prefixes.each do |prefix|
-      (1..4).each do |n|
-        create_merge_request(
-          title: "#{prefix} This is a title",
-          draft: false,
-          state_id: n
-        )
-      end
-    end
-
-    stub_const("#{described_class}::BATCH_SIZE", 1)
-  end
-
-  it 'schedules BackfillDraftStatusOnMergeRequests background jobs' do
-    Sidekiq::Testing.fake! do
-      draft_mrs = Gitlab::BackgroundMigration::BackfillDraftStatusOnMergeRequests::MergeRequest.eligible
-
-      first_mr_id = draft_mrs.first.id
-      second_mr_id = draft_mrs.second.id
-
-      freeze_time do
-        migrate!
-
-        expect(BackgroundMigrationWorker.jobs.size).to eq(7)
-        expect(described_class::MIGRATION)
-          .to be_scheduled_delayed_migration(2.minutes, first_mr_id, first_mr_id)
-        expect(described_class::MIGRATION)
-          .to be_scheduled_delayed_migration(4.minutes, second_mr_id, second_mr_id)
-      end
-    end
-  end
-end