Adjust indexes as per feedback

- obsolete one due to being superseeded
- redo one due to timing benefits with index

db/migrate/20200306192548_add_index_on_project_id_and_type_to_services.rb

@@ -4,14 +4,19 @@ class AddIndexOnProjectIdAndTypeToServices < ActiveRecord::Migration[6.0]
   include Gitlab::Database::MigrationHelpers
 
   DOWNTIME = false
+  INDEX_NAME = 'index_services_on_project_id'
 
   disable_ddl_transaction!
 
   def up
     add_concurrent_index :services, [:project_id, :type]
+
+    remove_concurrent_index_by_name :services, INDEX_NAME
   end
 
   def down
     remove_concurrent_index :services, [:project_id, :type]
+
+    add_concurrent_index :services, :project_id, name: INDEX_NAME
   end
 end

db/migrate/20200306193236_add_index_on_creator_id_and_created_at_to_projects.rb

+# frozen_string_literal: true
+
+class AddIndexOnCreatorIdAndCreatedAtToProjects < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+  INDEX_NAME = 'index_projects_on_creator_id'
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index :projects, [:creator_id, :created_at]
+
+    remove_concurrent_index_by_name :projects, INDEX_NAME
+  end
+
+  def down
+    remove_concurrent_index :projects, [:creator_id, :created_at]
+
+    add_concurrent_index :projects, :creator_id, name: INDEX_NAME
+  end
+end

db/migrate/20200306193236_add_index_on_id_and_creator_id_to_projects.rb

-# frozen_string_literal: true
-
-class AddIndexOnIdAndCreatorIdToProjects < ActiveRecord::Migration[6.0]
-  include Gitlab::Database::MigrationHelpers
-
-  DOWNTIME = false
-
-  disable_ddl_transaction!
-
-  def up
-    add_concurrent_index :projects, [:id, :creator_id]
-  end
-
-  def down
-    remove_concurrent_index :projects, [:id, :creator_id]
-  end
-end

db/schema.rb

@@ -3471,9 +3471,8 @@ ActiveRecord::Schema.define(version: 2020_03_11_165635) do
     t.index ["created_at", "id"], name: "index_projects_api_vis20_created_at", where: "(visibility_level = 20)"
     t.index ["created_at", "id"], name: "index_projects_on_created_at_and_id"
     t.index ["creator_id", "created_at"], name: "index_projects_on_mirror_creator_id_created_at", where: "((mirror = true) AND (mirror_trigger_builds = true))"
-    t.index ["creator_id"], name: "index_projects_on_creator_id"
+    t.index ["creator_id", "created_at"], name: "index_projects_on_creator_id_and_created_at"
     t.index ["description"], name: "index_projects_on_description_trigram", opclass: :gin_trgm_ops, using: :gin
-    t.index ["id", "creator_id"], name: "index_projects_on_id_and_creator_id"
     t.index ["id", "repository_storage", "last_repository_updated_at"], name: "idx_projects_on_repository_storage_last_repository_updated_at"
     t.index ["id"], name: "index_on_id_partial_with_legacy_storage", where: "((storage_version < 2) OR (storage_version IS NULL))"
     t.index ["id"], name: "index_projects_on_id_partial_for_visibility", unique: true, where: "(visibility_level = ANY (ARRAY[10, 20]))"