TencentDB for SQL Server is licensed by Microsoft, ensuring users have access to the latest features and mitigating the risks associated with using unlicensed software. It offers characteristics such as immediate availability, stability, reliability, secure operation, and elastic scalability. Additionally, it incorporates a high-availability architecture, data reliability, and fault recovery capabilities, which help enhance the stability and availability of your database service.
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SQL Server is one of the earlier commercially released database products. It supports complex SQL queries, delivers excellent performance, and provides robust support for applications built on the Windows platform with the .NET architecture. It is widely used across sectors such as government, finance, healthcare, retail, education, and gaming.
Descriptions in this product, such as "second-level automatic failover" and "second-level failover to primary node", indicate that under the appropriate architecture and configuration conditions, the product can support relatively fast failover/switch between primary and secondary and recovery. The actual recovery performance depends on the specific usage scenario and the product documentation.
Deployment Architecture
TencentDB for SQL Server supports 3 types of instance deployment architectures: single-node, two-node, and multi-node.
Single-Node (Formerly Basic Edition)
The single-node architecture uses a single compute node for deployment. It offers good cost-effectiveness and the feature of granting the highest SA permissions (you need to submit a ticket to apply for creating an account with SA permissions). This architecture applies to lightweight scenarios. Its core advantages are low cost and high-level permissions. Compute node failures can be recovered by replacing the node, and disk failures can be rebuilt using disk snapshots, but the overall recovery time is relatively long. It primarily serves personal learning, non-core small systems of enterprises, and development and testing environments, meeting the flexible needs of low-load and non-critical businesses. The instance architecture displayed in the console is: Single-Node (Cloud Disk). Two-Node (Formerly HA/Cluster Edition)
The two-node architecture is based on a high-availability design with one primary node and one secondary node. The primary node provides read/write services, while the secondary node synchronizes data in real-time but is inaccessible. (The secondary node in the cloud disk architecture can be accessed.) For SQL Server 2012, 2014, and 2016 Enterprise editions, the primary/secondary two-node architecture consists of a one-primary-one-mirror SQL Server database. For SQL Server 2017, 2019, 2022, and 2025 Enterprise editions, the primary/secondary two-node architecture adopts the always On architecture. Automatic failover and multi-AZ disaster recovery capabilities help enhance business continuity and data reliability. Its robust performance is well-suited for high-concurrency scenarios, such as e-commerce transactions, financial payments, multi-tenancy SaaS, and online game services. This makes it applicable to scenarios with high availability requirements, such as enterprise core production systems. The instance architecture displayed in the console for a two-node instance varies depending on the selected storage type: Two-Node (Local Disk) and Two-Node (Cloud Disk).
Multi-Node
The multi-node architecture adopts the always On architecture design of one-primary-multiple-secondary + compute-storage separation. It supports SQL Server 2017, 2019, 2022, and 2025 Enterprise editions. The primary node provides read/write services, while the secondary nodes provide read-only services and support second-level failover to the primary node. This achieves multi-AZ disaster recovery and elastic scalability. By dynamically adding or removing nodes and adjusting resources on demand, this architecture meets the requirements of high read performance for massive data, frequent scaling, and multi-active disaster recovery. It also provides technical support for customers in industries such as finance and government affairs to build high-availability architectures, manage business continuity, and meet relevant compliance requirements. This architecture applies to complex businesses (such as real-time analysis and multi-tenancy systems) and high-performance scenarios requiring read-write separation, balancing business flexibility and stability. The instance architecture displayed in the console is: Multi-Node (Cloud Disk).
Isolation Policy
Single-Node (Cloud Disk), Two-Node (Cloud Disk), and Multi-Node (Cloud Disk) instances for TencentDB for SQL Server are deployed on CVMs. Each instance exclusively occupies one CVM and has dedicated CPU, memory, and disk resources. Different instances are completely isolated from each other.
Two-Node (Local Disk) instances for TencentDB for SQL Server are deployed on local physical servers. Multiple instances are deployed on each physical server. Through isolation policies, strict isolation between different instances is ensured, with each instance having dedicated CPU, memory, and disk resources.
In addition, TencentDB for SQL Server has also implemented corresponding data isolation policies across multiple dimensions, including accounts, regions, AZs, and networks.
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The names and trademarks of SQL Server, Windows, .NET, and others are owned by Microsoft Corporation or its affiliates. Their use in this document is solely for the purpose of illustrating product compatibility and support.