What it is: An asynchronous copy of a database used primarily for scaling reads.

What it’s for:

• Offload read traffic (reporting, dashboards, read-heavy workloads).
• Improve performance for read operations.

Key ideas:

• Replication is asynchronous (replica may lag behind).
• Read replicas have their own endpoint.
• Some engines allow promotion to standalone DB (disaster recovery pattern, but not “automatic same endpoint” like Multi-AZ).

Exam cues:

• “read-heavy workload, scale reads” → Read Replica.
• “replica lag is acceptable” → asynchronous replica.

Hard words:

• *asynchronous* /eɪˈsɪŋkrənəs/: bất đồng bộ
• *lag* /læɡ/: độ trễ (chậm hơn dữ liệu gốc)
• *promote* /prəˈmoʊt/: nâng cấp (thành primary)