Cloud SQL for PostgreSQL now supports PostgreSQL version 18 in Preview

## Feature Cloud SQL for PostgreSQL now supports PostgreSQL version 18 in [Preview](https://cloud.google.com/products#product-launch-stages). PostgreSQL 18 is a newly supported version. We strongly recommend that you review the changes in the release and validate the readiness of your instance thoroughly prior to upgrading your instance to this version. The following information applies to flags and extensions for PostgreSQL 18: **Flags** The following new flags are available for PostgreSQL 18 only: * `autovacuum_vacuum_max_threshold` * `autovacuum_worker_slots` * `enable_distinct_reordering` * `enable_self_join_elimitation` * `io_max_concurrency` * `io_method` * `io_workers` * `log_lock_failures` * `max_active_replecation_origins` * `track_cost_delay_timing` * `vacuum_max_eager_freeze_failure_rate` * `vacuum_truncate` For more information, see [Configure database flags](https://cloud.google.com/sql/docs/postgres/flags). **Extensions** The following extensions aren't available for PostgreSQL 18: * `pgRouting` * `plpgsql_check` * `pg_hint_plan` * `pgrouting` * `anonymizer` * `pg_wait_sampling` * `tds_fdw` For more information, see [Configure PostgreSQL extensions](https://cloud.google.com/sql/docs/postgres/extensions). To create a new instance using PostgreSQL 18, see [Create instances](https://cloud.google.com/sql/docs/postgres/create-instance).