ERROR 42501: Permission denied for table in Postgres

Error Message#

ERROR: permission denied for table users

Description#

This error occurs when a user attempts to perform an operation on a table without having the necessary privileges. It can happen during SELECT, INSERT, UPDATE, DELETE operations or when accessing tables through JOINs.

Causes#

• User lacks required permissions for the operation
• Missing schema usage permissions
• Incorrect search path configuration
• Role membership issues
• Row-level security policies blocking access

Solutions#

1. Grant appropriate permissions:

   -- Grant specific permission
   GRANT SELECT ON table_name TO user_name;
   
   -- Grant multiple permissions
   GRANT SELECT, INSERT, UPDATE ON table_name TO user_name;

2. Grant schema permissions:

   GRANT USAGE ON SCHEMA schema_name TO user_name;

3. Check current permissions:

   -- For tables
   SELECT grantee, privilege_type
   FROM information_schema.role_table_grants
   WHERE table_name = 'mytable';

4. Add user to role:

   GRANT role_name TO user_name;

Prevention#

• Plan permission structure before creating objects
• Use role-based access control instead of individual user permissions
• Document permission requirements in your database schema
• Test permissions in development environments