Adjust scheduling migration

db/post_migrate/20201208175117_schedule_backfilling_artifact_expiry_migration.rb

@@ -4,25 +4,35 @@ class ScheduleBackfillingArtifactExpiryMigration < ActiveRecord::Migration[6.0]
   include Gitlab::Database::MigrationHelpers
 
   DOWNTIME = false
-  INDEX_NAME = 'expired_artifacts_temp_index'
-  INDEX_CONDITION = 'expire_at IS NULL'
+  SWITCH_DATE = Time.utc(2020, 6, 22).freeze
+  INDEX_NAME = 'expired_artifacts_temp_index'.freeze
+  INDEX_CONDITION = "expire_at IS NULL AND created_at < '#{SWITCH_DATE}'"
 
   disable_ddl_transaction!
 
+  class JobArtifact < ActiveRecord::Base
+    include EachBatch
+
+    self.table_name = 'ci_job_artifacts'
+
+    scope :without_expiry_date, -> { where(expire_at: nil) }
+    scope :before_switch, -> { where('created_at < ?', SWITCH_DATE) }
+  end
+
   def up
     # Create temporary index for expired artifacts
     # Needs to be removed in a later migration
-    add_concurrent_index(:ci_job_artifacts, :expire_at, where: INDEX_CONDITION, name: INDEX_NAME)
+    add_concurrent_index(:ci_job_artifacts, %i(id created_at), where: INDEX_CONDITION, name: INDEX_NAME)
 
     queue_background_migration_jobs_by_range_at_intervals(
-      ::Ci::JobArtifact.where(expire_at: nil),
+      JobArtifact.without_expiry_date.before_switch,
       ::Gitlab::BackgroundMigration::BackfillArtifactExpiryDate,
       2.minutes,
-      batch_size: 100_000
+      batch_size: 200_000
     )
   end
 
   def down
-    # no-op
+    remove_concurrent_index_by_name :ci_job_artifacts, INDEX_NAME
   end
 end

db/structure.sql

@@ -20756,7 +20756,7 @@ CREATE UNIQUE INDEX epic_user_mentions_on_epic_id_and_note_id_index ON epic_user
 
 CREATE UNIQUE INDEX epic_user_mentions_on_epic_id_index ON epic_user_mentions USING btree (epic_id) WHERE (note_id IS NULL);
 
-CREATE INDEX expired_artifacts_temp_index ON ci_job_artifacts USING btree (expire_at) WHERE (expire_at IS NULL);
+CREATE INDEX expired_artifacts_temp_index ON ci_job_artifacts USING btree (id, created_at) WHERE ((expire_at IS NULL) AND (created_at < '2020-06-22 00:00:00+00'::timestamp with time zone));
 
 CREATE INDEX finding_links_on_vulnerability_occurrence_id ON vulnerability_finding_links USING btree (vulnerability_occurrence_id);