Read Replica is a database replica that is created from a master database to provide a read-only copy of the data. It is used to distribute read traffic to multiple copies of a database, thereby reducing the load on the master database and improving the performance of the application. Read replicas are used in read-heavy applications where the majority of the queries are reads.
For example, Amazon Web Services (AWS) offers an Amazon RDS service that allows users to create a read replica of their master database. The read replica is available for read-only queries and is updated asynchronously from the master database. This allows applications to scale their read capacity without adding additional load on the master database. Additionally, AWS RDS uses Multi-AZ deployments to ensure high availability for read replicas in case of a fault in the primary database.
Read replicas provide scalability and improve the read performance of an application.
A read replica is a copy of a source database instance that is created automatically and synchronously updated with the source.
Read replicas can be used in read-heavy workloads, analytics or reporting, and reducing the load on the source database instance.
With read replicas, database administrators can improve the availability and reliability of their systems by replicating data to different regions or availability zones.
Read replicas can be managed through various services such as Amazon RDS, Microsoft Azure, and Google Cloud Platform.
Read replicas can also be configured to use different instance types or databases to optimize performance and cost.
Read replicas can be promoted to become the new source database instance in case of failures or planned maintenance.
Consistency and durability of data are maintained between read replica and source instance through synchronous replication.
Additional read replicas can be added to scale read workloads further, and they are useful in scaling up data access for high numbers of concurrent users.
While read replicas improve read performance, they do not create a high-availability solution on their own – additional measures need to be taken in ensuring a high availability system.
Answer: A Read Replica is a relational database instance that is created to offload read traffic from a primary instance.
Answer: A Read Replica is an active copy of a database that can handle read-only queries, while a backup is a passive copy of a database that does not accept queries.
Answer: No, Read Replica cannot be used for failover purposes. It is used for scaling and offloading read traffic from the primary instance.
Answer: A Read Replica uses asynchronous replication to keep up with changes in the primary instance. Changes are made to the primary instance and then replicated to the Read Replica.
Answer: Yes, it is possible to have a Read Replica in a different region or availability zone from the primary instance. This provides redundancy and can help with disaster recovery.