How Long Is the Primary/Standby Replication Delay?

If the replication thread is running properly, replication delay is a value measured in seconds. Replication delay is NULL if the SQL thread is abnormal, or if the I/O thread is running normally but the SQL thread has applied all relay logs.

The delay for primary/standby replication cannot be calculated using a formula as the delay is affected by the following factors:

• Network communication conditions.
• Transaction pressure on the primary instance, specifically the number of transactions executed per second on the primary instance.
• Transaction size on the primary instance, specifically how long a single transaction takes to execute.
• Loads on the standby instance and read replicas

If the primary DB instance is under heavy load for a period of time and executes a large number of transactions per second, replication to the standby DB instance will usually be delayed. Otherwise, the replication delay is generally in seconds.

Click the DB instance name on the Instances page. The replication source is the primary DB instance. When the replication status is normal, check the primary/standby replication latency.