Limitations
A high availability DB system has certain limitations.
- A high availability DB system performs rolling upgrades, which has a brief period of downtime before the newly promoted MySQL instance resumes connections. Each MySQL instance is upgraded separately. See Maintenance of a High Availability DB System.
- High availability is supported for version 8.0.24 of MySQL, or higher. You cannot create a highly available DB system using a backup from a DB system with an earlier version.
- You can access the MySQL instance that functions as the primary instance only. You cannot access the other two secondary instances directly, using MySQL Shell, or any other such client.
- The maximum size of transaction depends to the amount of memory of the shape. The memory of the shapes and associated transaction size limits (in bytes) are as follows:
- 8GB: 85,899,346
- 16GB: 171,798,692
- 32GB: 343,597,384
- 64GB: 687,194,767
- 128GB or more: 1,073,741,824
- If a HeatWave cluster load or reload operation is going on, enabling or disabling high availability can fail. It is recommended to not enable or disable high availability while a HeatWave cluster load or reload operation is going on.
- Prior to MySQL 8.3.0-u2, you cannot enable high availability on a DB system with HeatWave Lakehouse enabled.