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    Hologres:Suggestions on using Hologres

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    Hologres:Suggestions on using Hologres

    Last Updated:Jan 05, 2024

    To ensure the stability and security of your cluster, we recommend that you comply with restrictions on maximum values for items in the following table. Exceeded values of the following items may lead to system performance deterioration. Excessive loads may also make the system unstable and increase the risk of system crashes or service interruptions.

    Item

    Recommended maximum value

    Number of databases in an instance

    10

    Number of times for purchasing instances or scaling in or scaling out instances per day

    10

    Number of accounts (including Alibaba Cloud accounts, RAM users, and custom accounts) that can be added to an instance

    256

    Note

    For more information, see Manage users.

    Number of connections to an instance

    The maximum value varies based on instance specifications. For more information, see Instance types.

    Number of tables (including child partitioned tables and excluding foreign tables) in a table group

    10,000

    Note

    You can execute the following SQL statement to query the number of tables in each table group in the current database:

    SELECT
 property_value,
 count(1)
FROM
 hologres.hg_table_properties
WHERE
 property_key = 'table_group'
GROUP BY 1 ;

    Number of columns (fields) in a table

    • Column-oriented table: no more than 300 columns

    • Row-oriented table: no more than 3,000 columns

    • Row-column hybrid table: no more than 300 columns

    Total number of columns in all tables in a table group

    1,000,000

    Maximum length of a table comment

    1,024 characters

    Maximum length of a column comment

    1,024 characters

    Maximum amount of data that can be stored in a value (supported data types: TEXT, CHAR, VARCHAR, JSON, JSONB, BLOB, BYTEA, BIT, and VARBIT)

    4 MB

    If you want to use a value that exceeds the recommended maximum value, join the Hologres DingTalk group for technical support. For more information, see Obtain online support for Hologres.