How to Create a Read-Only user in PostgreSQL?
How to Create a Read-Only user in PostgreSQL?
Creating a read-only user in PostgreSQL is useful when you want to allow certain users to view data in a database without making any modifications. This is particularly beneficial for reporting, analytics, or providing limited access to external stakeholders.
In PostgreSQL, setting up a read-only user involves:
- Creating a new user.
- Granting access to the necessary database.
- Assigning permissions on specific tables (or the entire schema) for read-only access.
Steps to Create a Read-Only user
1. Create the Read-Only user
-- Create a new user with a password CREATE USER readonly_user WITH PASSWORD 'password';
Explanation:
- CREATE USER readonly_user: Defines a new user named readonly_user.
- WITH PASSWORD 'password': Sets the password for the new user.
2. Grant Access to the Database
Code:
-- Grant the CONNECT privilege on the database to the user GRANT CONNECT ON DATABASE your_database TO readonly_user;
Explanation:
- GRANT CONNECT ON DATABASE your_database: Allows readonly_user to connect to your_database.
3. Grant Usage on the Schema
-- Grant usage on the public schema, enabling access to the schema's structure GRANT USAGE ON SCHEMA public TO readonly_user;
Explanation:
- GRANT USAGE ON SCHEMA public: Provides schema-level access so the user can see table structure but not modify data.
4. Grant Select Privileges on All Tables
To provide read-only access to all tables in a schema, you can use the following command:
-- Grant SELECT privilege on all tables in the public schema GRANT SELECT ON ALL TABLES IN SCHEMA public TO readonly_user;
Explanation:
- GRANT SELECT ON ALL TABLES IN SCHEMA public: Grants read-only access to every table in the specified schema (here, public).
5. Automate Future Table Permissions
To ensure that readonly_user retains read-only access to any new tables created in the future, set default privileges:
-- Set default privileges for future tables created in the schema ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON TABLES TO readonly_user;
Explanation:
- ALTER DEFAULT PRIVILEGES IN SCHEMA public: Sets default privileges on any new tables created in the public schema.
Example Code and Explanation
Suppose you want to create a read-only user named report_viewer for a database called sales_data.
1. Create the User
Code:
-- Step 1: Create the read-only user with a password
CREATE USER report_viewer WITH PASSWORD 'securepassword';
2. Grant Database Access
-- Step 2: Grant CONNECT privilege on the 'sales_data' database
GRANT CONNECT ON DATABASE sales_data TO report_viewer;
3. Grant Usage on the Schema
-- Step 3: Allow user to access the public schema's structure
GRANT USAGE ON SCHEMA public TO report_viewer;
4. Grant Select Privileges on Tables
-- Step 4: Grant SELECT privilege on all tables in the schema
GRANT SELECT ON ALL TABLES IN SCHEMA public TO report_viewer;
5. Set Default Privileges for Future Tables
-- Step 5: Ensure the user has read access to new tables created in the schema
ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON TABLES TO report_viewer;
Important Notes:
- Privileges: Only SELECT privileges are granted to maintain the read-only state.
- Default Privileges: Setting default privileges ensures any new tables created in the schema are also accessible to the read-only user.
- Schema Specific: This example assumes all tables are within the public schema. For other schemas, replace public with the relevant schema name.
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https://w3resource.com/PostgreSQL/snippets/create-read-only-user-postgresql.php
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