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Function Comparison

Updated at:Nov 20, 2020 GMT+08:00

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.
Table 1 Function comparisons

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

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