2024-04-11

Granting Read-Only Access in PostgreSQL: A Step-by-Step Guide

postgresql
  1. Create the User:

    • Use the CREATE ROLE command to create a new user, often called a role in PostgreSQL. For example:

      CREATE ROLE readonly_user WITH LOGIN PASSWORD 'your_password';
      
    • Replace 'readonly_user' with your desired username and 'your_password' with a strong password.

  2. Grant Connection Permissions:

  3. Grant Schema Permissions:

  4. Grant Read Permissions:

    • Grant the user permission to select data from tables. You can grant access to individual tables or all tables within a schema. Here's granting access to all tables in the 'public' schema:

      GRANT SELECT ON ALL TABLES IN SCHEMA public TO readonly_user;
      
    • Additionally, grant access to sequences if your tables use them for auto-incrementing IDs. You can use a similar GRANT SELECT command for sequences.

  5. Optional: Set Default Privileges (For New Tables):

    • The above steps grant access to existing tables. To automatically grant read access to new tables created in the 'public' schema, use:

      ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON TABLES TO readonly_user;
      
    • This ensures new tables are also accessible by the read-only user.

By following these steps, you create a user account with read-only access to a PostgreSQL database. This user can view data but cannot modify or delete it.



Creating the User and Granting Connection:

CREATE ROLE readonly_user WITH LOGIN PASSWORD 'your_strong_password';
GRANT CONNECT ON DATABASE my_database TO readonly_user;

Granting Schema and Read Permissions:

\c my_database  -- Connect to the specific database

GRANT USAGE ON SCHEMA public TO readonly_user;
GRANT SELECT ON ALL TABLES IN SCHEMA public TO readonly_user;
GRANT SELECT ON ALL SEQUENCES IN SCHEMA public TO readonly_user;

Setting Default Privileges (Optional):

ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON TABLES TO readonly_user;

Explanation:

  • Replace 'your_strong_password' with a secure password for the user.
  • Replace my_database with the actual name of the database you want to grant access to.
  • The \c my_database command connects you to the specific database for granting schema and read permissions.

Remember to adjust these examples based on your specific database name, schema names (if different from 'public'), and whether you want to grant access to all sequences.



  1. Granting SELECT on Specific Tables:

    Instead of granting access to all tables in a schema, you can be more granular and grant SELECT permission on specific tables the user needs to access. This might be useful if you have a large database and want to restrict access to sensitive data.

    GRANT SELECT ON TABLE table1, table2 TO readonly_user;
    

    Replace table1 and table2 with the actual names of the tables you want to grant access to.

  2. Roles with Limited Permissions:

    PostgreSQL allows creating custom roles with pre-defined permissions. You can create a role specifically for read-only access and assign it to users. This approach involves some additional setup but can be helpful for managing user permissions more efficiently, especially if you have many read-only users.

    Here's a basic example:

    CREATE ROLE read_only_role;
    
    GRANT CONNECT ON DATABASE my_database TO read_only_role;
    GRANT USAGE ON SCHEMA public TO read_only_role;
    GRANT SELECT ON ALL TABLES IN SCHEMA public TO read_only_role;
    GRANT SELECT ON ALL SEQUENCES IN SCHEMA public TO read_only_role;
    
    GRANT read_only_role TO readonly_user;
    

    This first creates a role named read_only_role with the necessary permissions. Then, the readonly_user is assigned this role, inheriting its permissions.

Remember to choose the approach that best suits your specific needs and security requirements.


postgresql

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