Add specialized index for verification reminder

db/post_migrate/20211220120402_add_index_on_ci_pipelines_user_id_id_failure_reason.rb

+# frozen_string_literal: true
+
+class AddIndexOnCiPipelinesUserIdIdFailureReason < Gitlab::Database::Migration[1.0]
+  disable_ddl_transaction!
+
+  INDEX_NAME = 'index_ci_pipelines_on_user_id_and_id_desc_and_user_not_verified'
+
+  def up
+    add_concurrent_index :ci_pipelines, [:user_id, :id], order: { id: :desc }, where: 'failure_reason = 3', name: INDEX_NAME
+  end
+
+  def down
+    remove_concurrent_index_by_name :ci_pipelines, INDEX_NAME
+  end
+end

db/schema_migrations/20211220120402

+157128732c321577b7fa7a1b3d252ff70a2a62b34cd1e6edea59da4e632a1755
\ No newline at end of file

db/structure.sql

@@ -25705,6 +25705,8 @@ CREATE INDEX index_ci_pipelines_on_user_id_and_created_at_and_source ON ci_pipel
 
 CREATE INDEX index_ci_pipelines_on_user_id_and_id_and_cancelable_status ON ci_pipelines USING btree (user_id, id) WHERE ((status)::text = ANY (ARRAY[('running'::character varying)::text, ('waiting_for_resource'::character varying)::text, ('preparing'::character varying)::text, ('pending'::character varying)::text, ('created'::character varying)::text, ('scheduled'::character varying)::text]));
 
+CREATE INDEX index_ci_pipelines_on_user_id_and_id_desc_and_user_not_verified ON ci_pipelines USING btree (user_id, id DESC) WHERE (failure_reason = 3);
+
 CREATE INDEX index_ci_project_mirrors_on_namespace_id ON ci_project_mirrors USING btree (namespace_id);
 
 CREATE UNIQUE INDEX index_ci_project_mirrors_on_project_id ON ci_project_mirrors USING btree (project_id);