RDS Read-Replicas Flashcards
What are RDS Read Replicas?
RDS Read Replicas allow you to create one or more read-only copies of your database instance. These replicas help scale out read operations and offload read traffic from the primary database in a high-volume read environment.
How do RDS Read Replicas work?
RDS Read Replicas work by using the replication feature of the source database to asynchronously copy data to the replica. This ensures the replica contains a near-real-time copy of the source database.
What databases support RDS Read Replicas?
Amazon RDS supports Read Replicas for MySQL, PostgreSQL, MariaDB, Oracle, and SQL Server database engines.
What are the benefits of using RDS Read Replicas?
Benefits include improved application performance by offloading reads, increased database availability, and enhanced disaster recovery capabilities.
Can RDS Read Replicas be created across AWS Regions?
Yes, RDS allows the creation of cross-region Read Replicas, which is beneficial for disaster recovery and reducing latency for globally distributed applications.
How does RDS Read Replica promotion work?
An RDS Read Replica can be promoted to become a standalone database instance. This operation is irreversible and involves a brief interruption as the replica is disassociated from the source database.
Can RDS Read Replicas handle writes?
No, RDS Read Replicas are read-only. All write operations must be performed on the primary database instance.
What is the replication lag for RDS Read Replicas?
Replication lag refers to the delay between when data is written to the primary database and when it becomes visible in the Read Replica. The lag can vary from a few milliseconds to a few minutes, depending on workload, network latency, and the database size.
Are there any limitations to using RDS Read Replicas?
Limitations include potential replication lag, which might result in slightly stale data, and the fact that each Read Replica incurs additional costs. Additionally, not all database features and types are supported for replication.
How do you monitor the performance and lag of RDS Read Replicas?
AWS provides monitoring tools such as Amazon CloudWatch to track metrics like CPU utilization, read IOPS, and replication lag, helping ensure that Read Replicas are performing optimally.
