Function Comparison
Single DB instances use the single-node architecture. In contrast to the mainstream primary/standby DB instances, a single DB instance contains only one node and has no slave node for fault recovery.
Advantage Comparison
- Single DB instances: supports the creation of read replicas and supports the queries of error logs and slow query logs. Different from primary/standby DB instances that have two database nodes, a single DB instance has only one node, reducing the price to half of primary/standby DB instances. If a node fails, the restoration will take a long time. Therefore, single DB instances are not recommended for sensitive services that have high requirements on database availability.
- Primary/Standby DB instances: uses the slave database node only for failover and restoration. The slave database node does not provide services. The performance of single DB instances is similar to or even higher than the primary/standby DB instances.
- Cluster instances: uses the Microsoft Always On architecture with one master node, one slave node, and up to five read-only nodes. It features higher availability, reliability, and scalability.
DB Engine |
Single |
Primary/Standby |
Cluster |
|---|---|---|---|
MySQL |
8.0 5.7 5.6 |
8.0 5.7 5.6 |
Not supported for now |
PostgreSQL |
Enhanced Edition 12, which is available only for users with the open beta test (OBT) permission. You can contact customer service to apply for the permission. 11 10 9.6 9.5 |
Enhanced Edition 12, which is available only for users with the open beta test (OBT) permission. You can contact customer service to apply for the permission. 11 10 9.6 9.5 |
Not supported for now |
Microsoft SQL Server |
2017 Standard Edition 2017 Web Edition 2016 Enterprise Edition 2016 Standard Edition 2016 Web Edition 2014 Standard Edition 2014 Web Edition 2014 Enterprise Edition 2012 Standard Edition 2012 Web Edition 2012 Enterprise Edition 2008 Standard Edition |
2017 Standard Edition 2016 Enterprise Edition 2016 Standard Edition 2014 Enterprise Edition 2014 Standard Edition 2012 Enterprise Edition 2012 Standard Edition 2008 Standard Edition |
2017 Enterprise Edition |
Number of nodes |
1 |
2 |
2 |
Specifications |
vCPUs: a maximum of 60 Memory: a maximum of 512 GB Storage space: a maximum of 4 TB |
vCPUs: a maximum of 60 Memory: a maximum of 512 GB Storage space: a maximum of 4 TB |
vCPUs: a maximum of 60 Memory: a maximum of 512 GB Storage space: a maximum of 4 TB |
Monitoring and alarms |
Supported |
Supported |
Supported |
Security group |
Supported |
Supported |
Supported |
Backups and restorations |
Supported |
Supported |
Supported |
Parameter settings |
Supported |
Supported |
Supported |
SSL |
Supported |
Supported |
Supported |
Log management |
Supported |
Supported |
Supported |
Read replicas (need to be created) |
Supported |
Supported |
Supported |
High-frequency monitoring |
Supported |
Supported |
Supported |
Primary/standby switchover or failover |
Not supported |
Supported |
Supported |
Standby DB instance migration |
Not supported |
Supported |
Supported |
