Create a Pulsar namespace with retention and backlog quota policies

Steps

1. Create a namespace under a tenant via: pulsar-admin namespaces create {tenant}/{namespace}
2. Set a retention policy to prevent data deletion before it is consumed: pulsar-admin namespaces set-retention {tenant}/{namespace} --size 10G --time 7d (size -1 means unlimited; time -1 means unlimited duration).
3. Set a backlog quota to limit unconsumed message accumulation: pulsar-admin namespaces set-backlog-quota {tenant}/{namespace} --limit 5G --limitTime 86400 --policy producer_request_hold (other policies: producer_exception, consumer_backlog_eviction).
4. Verify policies via: pulsar-admin namespaces get-retention {tenant}/{namespace} and pulsar-admin namespaces get-backlog-quotas {tenant}/{namespace}
5. Apply message TTL at the namespace level to automatically expire unconsumed messages after a period: pulsar-admin namespaces set-message-ttl {tenant}/{namespace} --messageTTL 3600 (seconds).