WHAT REPACK (CONCURRENTLY) COSTS WHILE IT RUNS

Summary from the TLDR Data newsletter

PostgreSQL 19 adds built-in REPACK (CONCURRENTLY) for online table rewrites, avoiding extensions while generally running faster and generating less WAL than pg_repack or pg_squeeze. The tradeoffs are significant: it can delay VACUUM across the cluster, briefly block writes during the final swap, and currently has a ceiling of approximately 105 million updates/deletes per run.