Running CREATE EXTENSION IF NOT EXISTS vector inside a regular migration (executed by the application's DB user, not a superuser) succeeds on Railway Postgres 16. Did not need to open a psql shell or request an extension to be pre-installed. Verified by deploying a Go service whose first migration creates the extension and an HNSW index on a vector(768) column.
Railway managed PostgreSQL, version 16, March 2026 onwards.
