Long-running or idle transactions prevent transaction ID freezing

Long-running transactions or idle transactions holding old snapshots prevent autovacuum from advancing relfrozenxid. Freezing cannot progress past oldest active transaction snapshot, causing transaction ID age to continue increasing.

During wraparound recovery, identify and terminate long-running or idle transactions: pg_stat_activity for transactions with old xact_start. Set statement_timeout and idle_in_transaction_session_timeout to prevent unbounded transactions. Monitor postgresql.activity.xact_start_age.