# See http://doc.gitlab.com/ce/development/migration_style_guide.html# for more information on how to write migrations for GitLab.classAddUniqueIndexForEnvironmentSlug<ActiveRecord::MigrationincludeGitlab::Database::MigrationHelpersDOWNTIME=trueDOWNTIME_REASON='Adding a *unique* index to environments.slug'disable_ddl_transaction!defchangeadd_concurrent_index:environments,[:project_id,:slug],unique: trueendend