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    ApsaraDB for ClickHouse:Limits

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    ApsaraDB for ClickHouse:Limits

    Last Updated:Mar 28, 2026

    This topic describes usage limits for ApsaraDB for ClickHouse.

    Cluster purchase and configuration limits

    DescriptionLimit
    Maximum clusters per Alibaba Cloud account30
    Maximum node groups per cluster24
    Maximum database accounts per cluster500
    Scale-out, scale-in, and upgrade/downgrade operations per cluster per day12
    Maximum databases per cluster256

    Specification limits

    The following table shows the memory reserved by the underlying operating system and management services for each resource type.

    ResourceOS memory usageManagement service memory usage
    Compute node800 MB–13 GB (increases with specification size)~500 MB
    ZooKeeper800 MB–2.5 GB (increases with specification size)~500 MB

    Feature limits

    • High-availability clusters must use replicated table engines.

    • By default, all servers automatically form a cluster named default. Use the ON CLUSTER default clause to execute Data Definition Language (DDL) statements across all servers.

    • Configuring remote_servers is not supported.

    • The File and URL table engines are not supported.

    • The File and URL table functions are not supported.

    • Custom user Profiles are not supported.

    Object naming limits

    ObjectNaming ruleRestriction
    Database nameMust start with a lowercase letter. Can contain letters, digits, and underscores (_). Cannot contain two or more consecutive underscores. Maximum 64 characters.Cannot be system — this name is reserved for a built-in database.
    Table nameMust start with a letter or underscore (_). Can contain letters, digits, and underscores (_). Length: 1–127 characters.Cannot contain quotation marks, exclamation marks (!), or spaces. Cannot be a SQL reserved keyword.
    Column nameMust start with a letter or underscore (_). Can contain letters, digits, and underscores (_). Length: 1–127 characters.Cannot contain quotation marks, exclamation marks (!), or spaces. Cannot be a SQL reserved keyword.
    Account nameMust start with a lowercase letter and end with a lowercase letter or digit. Can contain lowercase letters, digits, and underscores (_). Length: 2–16 characters.—
    PasswordLength: 8–32 characters. Must include at least three of the following character types: uppercase letters, lowercase letters, digits, and special characters (!, @, #, $, %, ^, &, *, (), _, +, -, =).—

    Bandwidth limits

    Community-Compatible Edition

    Cluster bandwidth is determined by the Elastic Compute Service (ECS) specification bandwidth limits and disk performance.

    Enterprise Edition

    Disk storage

    TypeESSD_L1ESSD_L2
    Cluster read/write bandwidth (MB/s)min{120 × node count + 0.5 × total purchased storage, 460 × node count}min{120 × node count + 0.5 × total purchased storage, 980 × node count}

    OSS storage

    Per-node bandwidth depends on the Compute Unit (CCU) range and the region where your cluster is deployed.

    China (Beijing), China (Shanghai), China (Hangzhou), and China (Shenzhen)

    Cluster limits: Read 100 Gb/s, Write 20 Gb/s

    CCU rangePer-node read bandwidth (Gb/s)Per-node write bandwidth (Gb/s)QPS
    [4, 8)1.60.6Read: (max CCUs/node × 4) × 25; Write: (max CCUs/node × 4) × 2; Burst read: (max CCUs/node × 4) × 25 × 300; Burst write: (max CCUs/node × 4) × 2 × 300
    [8, 16)2.50.8Same formula as above
    [16, 32)4.11.0Same formula as above
    [32, 48)8.31.7Same formula as above
    [48, 64)10.82.2Same formula as above
    [64, 64]13.32.9Same formula as above
    Maximum CCUs per node = upper CCU limit / node count, where node count = 2 if the upper CCU limit is less than 64, or node count = upper CCU limit / 32 if the upper CCU limit is 64 or greater. Maximum memory per node (GB) = maximum CCUs per node × 4. For example, for a CCU range of [4, 8): max CCUs/node = 8 / 2 = 4, and max memory/node = 4 × 4 = 16 GB.

    China (Ulanqab)

    Cluster limits: Read 10 Gb/s, Write 10 Gb/s

    CCU rangePer-node read bandwidth (Gb/s)Per-node write bandwidth (Gb/s)
    [4, 8)1.01.0
    [8, 16)1.31.3
    [16, 32)1.61.6
    [32, 48)2.02.0
    [48, 64)2.62.6
    [64, 64]3.43.4

    Singapore

    Cluster limits: Read 100 Gb/s, Write 5 Gb/s

    CCU rangePer-node read bandwidth (Gb/s)Per-node write bandwidth (Gb/s)
    [4, 8)1.60.5
    [8, 16)2.50.65
    [16, 32)4.10.8
    [32, 48)8.31.0
    [48, 64)10.81.3
    [64, 64]13.31.7

    China (Hong Kong), Japan (Tokyo), US (Virginia), and Germany (Frankfurt)

    Cluster limits: Read 5 Gb/s, Write 5 Gb/s

    CCU rangePer-node read bandwidth (Gb/s)Per-node write bandwidth (Gb/s)
    [4, 8)2.00.5
    [8, 16)3.00.65
    [16, 32)5.00.8
    [32, 48)10.01.0
    [48, 64)13.01.3
    [64, 64]16.01.7
    For Enterprise Edition clusters in regions not listed above, use the limits for China (Hong Kong) as a reference.

    Read/write latency by storage class

    Storage classDomain name typeAccelerator4 KiB read latency (ms)4 KiB write latency (ms)
    OSS locally redundant storageStandard domain nameNo13.8–14.224.7–26.4
    DiskN/AN/A1.22.6