Add concurrent index for selecting resource_group from ci_builds

Changelog: performance

db/post_migrate/20210922084115_concurrent_index_resource_group_status_commit_id_for_ci_builds.rb

+# frozen_string_literal: true
+
+class ConcurrentIndexResourceGroupStatusCommitIdForCiBuilds < Gitlab::Database::Migration[1.0]
+  INDEX_NAME = 'index_ci_builds_on_resource_group_and_status_and_commit_id'
+
+  disable_ddl_transaction!
+
+  # Indexes were pre-created on gitlab.com to avoid slowing down deployments
+  # See: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/70279
+
+  # rubocop: disable Migration/PreventIndexCreation
+  def up
+    add_concurrent_index :ci_builds, [:resource_group_id, :status, :commit_id],
+      where: 'resource_group_id IS NOT NULL',
+      name: INDEX_NAME
+  end
+  # rubocop: enable Migration/PreventIndexCreation
+
+  def down
+    remove_concurrent_index_by_name :ci_builds, INDEX_NAME
+  end
+end

db/schema_migrations/20210922084115

+6401de932d87b684c8a00254231312f8633c66a8ea96670b2761442c771d3d7f
\ No newline at end of file

db/structure.sql

@@ -24442,6 +24442,8 @@ CREATE INDEX index_ci_builds_on_project_id_for_successfull_pages_deploy ON ci_bu
 
 CREATE INDEX index_ci_builds_on_queued_at ON ci_builds USING btree (queued_at);
 
+CREATE INDEX index_ci_builds_on_resource_group_and_status_and_commit_id ON ci_builds USING btree (resource_group_id, status, commit_id) WHERE (resource_group_id IS NOT NULL);
+
 CREATE INDEX index_ci_builds_on_runner_id_and_id_desc ON ci_builds USING btree (runner_id, id DESC);
 
 CREATE INDEX index_ci_builds_on_stage_id ON ci_builds USING btree (stage_id);