diff options
Diffstat (limited to 'db/migrate/20160810142633_remove_redundant_indexes.rb')
| -rw-r--r-- | db/migrate/20160810142633_remove_redundant_indexes.rb | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/db/migrate/20160810142633_remove_redundant_indexes.rb b/db/migrate/20160810142633_remove_redundant_indexes.rb new file mode 100644 index 00000000000..8641c6ffa8f --- /dev/null +++ b/db/migrate/20160810142633_remove_redundant_indexes.rb @@ -0,0 +1,112 @@ +# See http://doc.gitlab.com/ce/development/migration_style_guide.html +# for more information on how to write migrations for GitLab. + +class RemoveRedundantIndexes < ActiveRecord::Migration + include Gitlab::Database::MigrationHelpers + + DOWNTIME = false + + disable_ddl_transaction! + + def up + indexes = [ + [:ci_taggings, 'ci_taggings_idx'], + [:audit_events, 'index_audit_events_on_author_id'], + [:audit_events, 'index_audit_events_on_type'], + [:ci_builds, 'index_ci_builds_on_erased_by_id'], + [:ci_builds, 'index_ci_builds_on_project_id_and_commit_id'], + [:ci_builds, 'index_ci_builds_on_type'], + [:ci_commits, 'index_ci_commits_on_project_id'], + [:ci_commits, 'index_ci_commits_on_project_id_and_committed_at'], + [:ci_commits, 'index_ci_commits_on_project_id_and_committed_at_and_id'], + [:ci_commits, 'index_ci_commits_on_project_id_and_sha'], + [:ci_commits, 'index_ci_commits_on_sha'], + [:ci_events, 'index_ci_events_on_created_at'], + [:ci_events, 'index_ci_events_on_is_admin'], + [:ci_events, 'index_ci_events_on_project_id'], + [:ci_jobs, 'index_ci_jobs_on_deleted_at'], + [:ci_jobs, 'index_ci_jobs_on_project_id'], + [:ci_projects, 'index_ci_projects_on_gitlab_id'], + [:ci_projects, 'index_ci_projects_on_shared_runners_enabled'], + [:ci_services, 'index_ci_services_on_project_id'], + [:ci_sessions, 'index_ci_sessions_on_session_id'], + [:ci_sessions, 'index_ci_sessions_on_updated_at'], + [:ci_tags, 'index_ci_tags_on_name'], + [:ci_triggers, 'index_ci_triggers_on_deleted_at'], + [:identities, 'index_identities_on_created_at_and_id'], + [:issues, 'index_issues_on_title'], + [:keys, 'index_keys_on_created_at_and_id'], + [:members, 'index_members_on_created_at_and_id'], + [:members, 'index_members_on_type'], + [:milestones, 'index_milestones_on_created_at_and_id'], + [:namespaces, 'index_namespaces_on_visibility_level'], + [:projects, 'index_projects_on_builds_enabled_and_shared_runners_enabled'], + [:services, 'index_services_on_category'], + [:services, 'index_services_on_created_at_and_id'], + [:services, 'index_services_on_default'], + [:snippets, 'index_snippets_on_created_at'], + [:snippets, 'index_snippets_on_created_at_and_id'], + [:todos, 'index_todos_on_state'], + [:web_hooks, 'index_web_hooks_on_created_at_and_id'], + + # These indexes _may_ be used but they can be replaced by other existing + # indexes. + + # There's already a composite index on (project_id, iid) which means that + # a separate index for _just_ project_id is not needed. + [:issues, 'index_issues_on_project_id'], + + # These are all composite indexes for the columns (created_at, id). In all + # these cases there's already a standalone index for "created_at" which + # can be used instead. + # + # Because the "id" column of these composite indexes is never needed (due + # to "id" already being indexed as its a primary key) these composite + # indexes are useless. + [:issues, 'index_issues_on_created_at_and_id'], + [:merge_requests, 'index_merge_requests_on_created_at_and_id'], + [:namespaces, 'index_namespaces_on_created_at_and_id'], + [:notes, 'index_notes_on_created_at_and_id'], + [:projects, 'index_projects_on_created_at_and_id'], + [:users, 'index_users_on_created_at_and_id'], + ] + + transaction do + indexes.each do |(table, index)| + remove_index(table, name: index) if index_exists_by_name?(table, index) + end + end + + add_concurrent_index(:users, :created_at) + add_concurrent_index(:projects, :created_at) + add_concurrent_index(:namespaces, :created_at) + end + + def down + # We're only restoring the composite indexes that could be replaced with + # individual ones, just in case somebody would ever want to revert. + transaction do + remove_index(:users, :created_at) + remove_index(:projects, :created_at) + remove_index(:namespaces, :created_at) + end + + [:issues, :merge_requests, :namespaces, :notes, :projects, :users].each do |table| + add_concurrent_index(table, [:created_at, :id], + name: "index_#{table}_on_created_at_and_id") + end + end + + # Rails' index_exists? doesn't work when you only give it a table and index + # name. As such we have to use some extra code to check if an index exists for + # a given name. + def index_exists_by_name?(table, index) + indexes_for_table[table].include?(index) + end + + def indexes_for_table + @indexes_for_table ||= Hash.new do |hash, table_name| + hash[table_name] = indexes(table_name).map(&:name) + end + end +end |