Transaction ID wraparound shutdown risk

When PostgreSQL approaches the transaction ID wraparound limit, it issues warnings. If the limit is reached, PostgreSQL shuts down to prevent data corruption. Indicates autovacuum is severely behind.

Run aggressive manual vacuum immediately: vacuumdb --analyze --verbose --jobs=4 mydb. Reduce autovacuum_vacuum_scale_factor from 0.2 to 0.01. Increase autovacuum_max_workers from 3 to 5 or 6. Monitor oldest xmin age.