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    ApsaraDB RDS:Usage limits

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    ApsaraDB RDS:Usage limits

    Last Updated:Mar 28, 2026

    ApsaraDB RDS for SQL Server enforces the following limits to maintain instance stability and security. Review feature availability and database count limits before you provision or upgrade an instance.

    Feature support by edition

    The table below shows feature availability across RDS editions and SQL Server versions. Features marked Supported\* have conditions — see the notes after the table.

    FeatureRDS Cluster EditionRDS High-availability EditionRDS High-availability Edition (2008 R2)RDS Basic Edition
    SQL Server versions2025 EE / 2022 EE / 2019 EE / 2017 EE2025 SE / 2022 SE / 2019 SE / 2017 SE / 2016 SE/EE / 2014 SE/EE / 2012 SE/EE2008 R22025 SE/EE / 2022 Web/SE/EE / 2019 Web/SE/EE / 2017 Web/SE/EE / 2016 Web/SE/EE / 2014 SE / 2012 Web/EE (single-node)
    Max databases300 (formula-based)300 (formula-based)50400 (formula-based)
    Max database accountsUnlimitedUnlimited500Unlimited
    Max client connectionsUnlimitedUnlimitedDepends on the instance typeUnlimited
    Create users, logins, or databasesSupportedSupportedSupportedSupported
    Database-level DDL triggersSupportedSupportedNot supportedSupported
    Authorization within databasesSupportedSupportedNot supportedSupported
    Terminate threadsSupportedSupportedSupportedSupported
    Linked ServerSupported\*Supported\*Not supportedNot supported
    Distributed transactionSupportedSupportedNot supportedNot supported
    SQL ProfilerSupportedSupportedSupportedSupported
    Tuning AdvisorSupportedSupportedNot supportedSupported
    Change data capture (CDC)SupportedSupported (not supported for 2012 SE)Supported for cloud disks; not supported for Premium Local SSDsNot supported
    Change trackingSupportedSupportedNot supportedSupported
    Windows domain account logonSupported\*Supported\*Not supportedNot supported
    SQL Server Integration Services (SSIS)Supported\*Supported\*Not supportedSupported\*
    SQL Server Analysis Services (SSAS)
    SQL Server Reporting Services (SSRS)
    Asynchronous messagingSupportedSupportedSupportedSupported
    Database MailSupported†Supported†Not supportedSupported†
    R Services
    Common Language Runtime (CLR) integration
    Replication
    Policy Management

    **\* Condition — shared instance family:** Linked Server, Windows domain account logon, and SQL Server Integration Services (SSIS) are not available on instances that use the shared instance family.

    † Condition — Database Mail prerequisites: Before using Database Mail, create a host account and a System Admin (SA) account for the instance.

    Maximum number of databases

    The database limit for SQL Server 2008 R2 instances is fixed at 50. For all other versions, the limit depends on the instance type.

    RDS Cluster Edition and RDS High-availability Edition

    Formula: min(floor(√CPU cores) × 50, 300)

    1. Take the square root of the number of CPU cores.

    2. Round down to the nearest integer.

    3. Multiply by 50.

    4. The result, capped at 300, is the maximum number of databases.

    Example: A 4-core instance running SQL Server 2016 Standard Edition supports up to floor(√4) × 50 = 2 × 50 = 100 databases.

    RDS Basic Edition

    Formula: min(floor(√CPU cores) × 100, 400)

    1. Take the square root of the number of CPU cores.

    2. Round down to the nearest integer.

    3. Multiply by 100.

    4. The result, capped at 400, is the maximum number of databases.

    Example: A 4-core instance running SQL Server 2019 Standard Edition supports up to floor(√4) × 100 = 2 × 100 = 200 databases.

    The min function returns the smaller of two values. For example, min(100, 300) is 100.

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