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TencentDB for SQL Server
DocumentationTencentDB for SQL ServerOperation GuideConstraints and Limits
Constraints and Limits
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Last updated: 2025-01-06 11:20:31
Constraints and Limits
Last updated: 2025-01-06 11:20:31
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TencentDB for SQL Server service only offers instances with bundled licenses, meaning that upon creation, each instance is endowed with the corresponding version's Microsoft SQL Server software licensing authorization. It does not support the provision of licenses brought by users themselves.
In order to ensure the stability and security of instances, TencentDB for SQL Server has certain restrictions on usage as detailed below.
TencentDB for SQL Server is available in two editions: single-node edition (formerly Basic Edition) and two-node edition (formerly High Availability/Cluster Edition), each with its own set of features. For more information, see Features and Differences.
Note:
TencentDB for SQL Server does not support access to external applications through the database instance; it only permits access to the database instance via external applications.
If you have other questions about usage restrictions, submit a ticket for assistance.
Feature
Two-Node Edition
Single-Node Edition
Database version
2008 R2 Enterprise 2012 Enterprise 2014 Enterprise 2016 Enterprise 2017 Enterprise 2019 Enterprise 2022 Enterprise
Maximum number of databases (subject to the number of instance CPU cores as described in Constraints and Limits > Database quantity)
2008 R2 version: 300
2012, 2014, and 2016 versions: 300
2017, 2019, and 2022 versions: 100
400
Maximum number of database accounts
Unlimited
Unlimited
Database creation
Supported
Supported
User/Login account creation and deletion
Supported
Supported
SA account creation
Not supported
Supported
Database authorization
Supported
Supported
Database-level DDL trigger
Supported
Supported
Thread killing permission
Supported
Supported
SQL profiler
Supported
Supported
Publish/Subscribe
Supported
Not supported
Optimization advisor
Not supported
Supported
Linked server
For a detailed explanation, please refer to Limitations of the Linked Server Features.
Distributed transaction
Only supported by two-node local disk instances
Not supported
Change data capture (CDC)
Supported
Supported
Change tracking (CT)
Supported
Supported
Windows domain account login
Not supported
Not supported
Email
Not supported
Not supported
SQL Server Integration Services (SSIS)
Supported
Supported
SQL Server Analysis Services (SSAS)
Not supported
Not supported
SQL Server Reporting Services (SSRS)
Not supported
Not supported
R language service
Not supported
Not supported
Common Language Runtime (CLR) integration
Not supported
Not supported
Async messaging
Not supported
Not supported
Policy management
Not supported
Not supported

Database quantity

Note:
If the instance only has one CPU core, we recommend that you keep the database quantity limit at 70 to guarantee instance stability.
The maximum number of databases that can be created for instances of different specifications is related to the value of the max worker threads parameter. If the parameter uses the default value of 0, the maximum number of databases that can be created for instances of different versions and specifications is 80. If the value of this parameter is set to 20000 or higher, the maximum number of databases that can be created for instances of different versions and specifications is related to the number of CPU cores of an instance. You can refer to the calculation formula below. For information on how to set the parameters, see Setting Instance Parameters.
SQL Server 2008 R2 Enterprise instances don't support lifting the database quantity limit, which is 70. The limit in other SQL Server instances is subject to the number of instance CPU cores as calculated below:
Two-node (formerly High Availability Edition) 2012 Standard/Enterprise 2014 Standard/Enterprise 2016 Standard/Enterprise Maximum number of databases:

Extract the square root of the CPU core quantity, round it to one decimal place, multiply the result by 40, and add the product to 80 to get the value X. The smaller value between X and 300 is the maximum number of databases. For example, you can create up to 160 databases in a 4-core 16 GB MEM SQL Server 2014 Enterprise instance.
Two-node (formerly Cluster Edition) 2017 Enterprise 2019 Enterprise 2022 Enterprise
The maximum number of databases is related to the instance CPU. The maximum number of databases for instances with 8-core CPU or less is 80, and the maximum number of databases for instances with 8-core CPU or above is 100.
Single-node (formerly Basic Edition) 2008 R2 Enterprise 2012 Enterprise 2014 Enterprise 2016 Enterprise 2017 Enterprise 2019 Enterprise
2022 Enterprise Maximum number of databases:

Extract the square root of the CPU core quantity, round it down to the nearest integer, and multiply the result by 100 to get the value N. The smaller value between N and 400 is the maximum number of databases. For example, you can create up to 200 databases in a 4-core 16 GB MEM SQL Server 2017 Enterprise instance.
Table of instance CPU core quantity and corresponding database quantity limit
Database quantity limit for two-node edition (formerly High Availability/Cluster Edition)
Database quantity limit for single-node edition (formerly Basic Edition)
CPU cores
Two-node 2008 R2/2012/2014/2016 Enterprise
Two-node 2017/2019/2022 Enterprise
1
70
70
2
136
176
4
160
200
8
193
233
12
218
258
16
240
280
24
275
315
32
300
340
48
300
340
64
300
340
96
300
340
Number of CPU Cores
Single Node 2008 R2 Enterprise Edition
Single-node 2012/2014/2016/2017/2019/2022 Enterprise Edition
2
80
100
4
80
200
8
80
200
12
80
300
16
80
400
24
80
400
32
80
400
48
80
400
64
80
400

Linked Server Limitations

Linked servers are not supported between other clouds or self-built environments and Tencent Cloud and are only supported for a Tencent Cloud private network. However, within the TencentDB for SQL Server instance architecture, there are the following restrictions:
1. Cross-Architecture Scenarios
Cross-Architecture Direction
Description
Two-node instance → single-node instance
Not supported.
Single-node instance → two-node instance
Not supported.
Local disk instance → cloud disk instance
Not supported.
Cloud disk instance → local disk instance
Not supported.
2. Between Two-Node Instances
Cross-Architecture Direction
Description
Two-node local disk instance → two-node local disk instance
Interconnection is supported between domestic regions, and interconnection is supported between overseas regions, but not between domestic and overseas regions.
Two-node cloud disk instance → two-node cloud disk instance
Only interconnection within the same region is supported.
3. Between Single Node Instances
Interconnection is supported only when the source and target are the same instance.
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