The following steps show how to promote the read replica to The general process of a single-zone database instance.
>Stop writing any transactions to the read replica source database instance, and then wait for all updates to the read replica. The read replica occurs on the source database instance. Database updates will occur after the update, and this replication “lag” may vary greatly. Use the “replica lag” metric to determine when all updates have been made to the read replica.
>To be able to perform the read replica To change, the read_only parameter must be set to 0 in the database parameter group of the read replica.
>Perform all necessary DDL operations on the read replica, such as creating an index. Operations performed on the read replica will not affect the source database The performance of the instance.
>Use the “Promote Read Replica” option on the RDS console, CLI command rds-promote-read-replica or PromoteReadReplica API operation to improve the read replica.
Pay attention to the promotion The process takes a few minutes to complete. When the read replica is promoted, replication will be stopped and the read replica will be restarted. After the restart is complete, the read replica can be used as a single-zone database instance.
I tried to promote the read replica to a separate RDS instance. During this time it was completed for almost 10 minutes. As far as I know, it should break the replication process and synchronize the time lag. But I found the situation in EC2 RDS , The db instance will also be restarted. Can someone explain the whole process clearly to me.
According to http://docs.aws.amazon.com/AmazonRDS/latest/ UserGuide/USER_ReadRepl.html restart is part of the process:
The following steps show the general process of promoting a read replica to a single-AZ database instance.
>Stop Write any transaction to the source database instance of the read replica, and After waiting for all updates to the read replica. A database update occurs on the read replica after a database update on the source database instance, and this replication “lag” may vary greatly. Use the “replica lag” metric to determine when All updates have been made to the read replica.
>To be able to make changes to the read replica, the read_only parameter must be set to 0 in the database parameter group of the read replica.
>Execute all necessary on the read replica DDL operations such as index creation. Operations performed on the read replica will not affect the performance of the source database instance.
>Use the “Promote Read Replica” option on the RDS console, and the CLI command rds-promote-read- Replica or PromoteReadReplica API operation to promote the read replica.
Note that the promotion process takes a few minutes to complete. When the read replica is promoted, replication will be stopped and the read replica will be restarted. After the restart is complete, read-only The copy can be used as a single-zone database instance.