Simplify migration and use plain SQL

db/post_migrate/20200127111840_fix_projects_without_project_feature.rb

@@ -3,7 +3,7 @@
 class FixProjectsWithoutProjectFeature < ActiveRecord::Migration[5.2]
   include Gitlab::Database::MigrationHelpers
 
-  BATCH_SIZE = 100_000
+  BATCH_SIZE = 50_000
 
   disable_ddl_transaction!
 

lib/gitlab/background_migration/fix_projects_without_project_feature.rb

@@ -2,61 +2,59 @@
 
 module Gitlab
   module BackgroundMigration
-    # Project model for this migration
-    class Project < ActiveRecord::Base
-      include EachBatch
-    end
-
-    ENABLED = 20
-    INSERT_BATCH_SIZE = 10_000
-
     # This migration creates missing project_features records
     # for the projects within the given range of ids
     class FixProjectsWithoutProjectFeature
       def perform(from_id, to_id)
-        Project.transaction do
-          projects = Project.where(<<~SQL, from_id, to_id)
-            projects.id BETWEEN ? AND ?
-            AND NOT EXISTS (
-              SELECT 1 FROM project_features
-              WHERE project_features.project_id = projects.id
-            )
-          SQL
-
-          projects.each_batch(of: INSERT_BATCH_SIZE) do |batch|
-            insert_missing_records(batch)
-          end
+        if number_of_created_records = create_missing!(from_id, to_id) > 0
+          log(number_of_created_records, from_id, to_id)
         end
       end
 
       private
 
-      def insert_missing_records(projects)
-        features = projects.map do |project|
-          record = {
-            project_id: project.id,
-            merge_requests_access_level: ENABLED,
-            issues_access_level: ENABLED,
-            wiki_access_level: ENABLED,
-            snippets_access_level: ENABLED,
-            builds_access_level: ENABLED,
-            repository_access_level: ENABLED,
-            pages_access_level: ENABLED,
-            forking_access_level: ENABLED
-          }
-
-          record['created_at'] = record['updated_at'] = Time.now.to_s(:db)
-
-          record
+      def create_missing!(from_id, to_id)
+        result = ActiveRecord::Base.connection.select_one(sql, nil, [[nil, from_id], [nil, to_id]])
+        return 0 unless result
+
+        result['number_of_created_records']
+      end
+
+      def sql
+        <<~SQL
+          WITH created_records AS (
+            INSERT INTO project_features (
+              project_id,
+              merge_requests_access_level,
+              issues_access_level,
+              wiki_access_level,
+              snippets_access_level,
+              builds_access_level,
+              repository_access_level,
+              pages_access_level,
+              forking_access_level,
+              created_at,
+              updated_at
+            )
+              SELECT projects.id, 20, 20, 20, 20, 20, 20, 20, 20, NOW(), NOW()
+              FROM projects
+              WHERE projects.id BETWEEN $1 AND $2
+              AND NOT EXISTS (
+                SELECT 1 FROM project_features
+                WHERE project_features.project_id = projects.id
+              )
+            ON CONFLICT (project_id) DO NOTHING
+            RETURNING *
+          )
+          SELECT COUNT(*) as number_of_created_records
+          FROM created_records
+        SQL
       end
 
-        Gitlab::Database.bulk_insert(:project_features, features, on_conflict: :do_nothing)
-
-        logger.info(message: "FixProjectsWithoutProjectFeature: created missing project_features for Projects #{projects.map(&:id).join(', ')}")
-      end
+      def log(count, from_id, to_id)
+        logger = Gitlab::BackgroundMigration::Logger.build
 
-      def logger
-        @logger ||= Gitlab::BackgroundMigration::Logger.build
+        logger.info(message: "FixProjectsWithoutProjectFeature: created missing project_features for #{count} projects in id=#{from_id}...#{to_id}")
       end
     end
   end

spec/lib/gitlab/background_migration/fix_projects_without_project_feature_spec.rb

@@ -25,10 +25,30 @@ describe Gitlab::BackgroundMigration::FixProjectsWithoutProjectFeature, :migrati
     ActiveRecord::Base.connection.select_one('SELECT MIN(id), MAX(id) FROM projects').values
   end
 
-  it 'creates a default ProjectFeature for projects without it' do
+  it 'creates a ProjectFeature for projects without it' do
     expect { subject }.to change { project_feature_records }.from([project.id]).to([project.id, *projects_without_feature.map(&:id)])
   end
 
+  it 'creates ProjectFeature records with default values' do
+    subject
+
+    project_id = projects_without_feature.first.id
+    record = ActiveRecord::Base.connection.select_one('SELECT * FROM project_features WHERE id=$1', nil, [[nil, project_id]])
+
+    expect(record.except('id', 'project_id', 'created_at', 'updated_at')).to eq(
+      {
+        "merge_requests_access_level" => 20,
+        "issues_access_level" => 20,
+        "wiki_access_level" => 20,
+        "snippets_access_level" => 20,
+        "builds_access_level" => 20,
+        "repository_access_level" => 20,
+        "pages_access_level" => 20,
+        "forking_access_level" => 20
+      }
+    )
+  end
+
   it 'sets created_at/updated_at timestamps' do
     subject