How to fix Must be owner of table in PostgreSQL

First, identify the current table owner by querying the PostgreSQL system catalogs:

SELECT t.table_name, t.table_schema, u.usename as owner
FROM information_schema.tables t
JOIN pg_catalog.pg_class c ON (t.table_name = c.relname)
JOIN pg_catalog.pg_user u ON (c.relowner = u.usesysid)
WHERE t.table_schema = 'public' AND t.table_name = 'your_table_name';

Or for a specific table:

SELECT tableowner FROM pg_tables WHERE tablename = 'your_table_name';

Compare the owner column with your current user (check via SELECT CURRENT_USER;).

If you have superuser privileges, transfer ownership to the user who needs to manage the table:

ALTER TABLE public.your_table_name OWNER TO current_user;

Or explicitly specify the username:

ALTER TABLE public.your_table_name OWNER TO application_user;

After this, the new owner can perform all DDL operations on that table.

If running database migrations (Liquibase, Alembic, Prisma migrate), ensure the migration runner uses the correct database role:

# PostgreSQL connection string with explicit user
DATABASE_URL="postgresql://app_user:password@localhost:5432/mydb"
npx prisma migrate deploy

The user in the connection string must be the owner of the tables being migrated. Create a role that owns all application tables:

CREATE ROLE app_owner;
ALTER ROLE app_owner LOGIN PASSWORD 'secure_password';
ALTER ROLE app_owner CREATEDB;

-- When creating tables, connect as app_owner
ALTER TABLE existing_table OWNER TO app_owner;

In production environments, PostgreSQL best practice is to use role membership instead of giving direct table ownership to individual users:

-- Create a group role that owns all application tables
CREATE ROLE app_group NOLOGIN;

-- Grant membership to individual users
GRANT app_group TO app_user;
GRANT app_group TO app_admin;

-- All tables owned by app_group
CREATE TABLE schema.table_name (...) [with app_group as owner];

Users in the app_group role can then:
- ALTER, DROP, and modify tables (via role membership)
- Still authenticate with individual credentials
- Be added/removed from the group without changing table ownership

To set the role during DDL operations:

SET ROLE app_group;
ALTER TABLE table_name ADD COLUMN new_col INTEGER;

In development environments only, you can temporarily grant superuser privileges to perform schema changes:

-- As superuser (postgres), temporarily enable superuser on application user
ALTER ROLE app_user SUPERUSER;

-- Run your migrations/DDL
-- Then revoke superuser
ALTER ROLE app_user NOSUPERUSER;

Do NOT use this in production. Superuser bypasses all security checks and should only be used by database administrators.

If you only need to CREATE new tables (not modify existing ones), grant schema privileges instead:

GRANT USAGE ON SCHEMA public TO app_user;
GRANT CREATE ON SCHEMA public TO app_user;

This allows the user to create new tables (which they will own), but they still cannot modify tables owned by other users. For modifying existing tables, only ownership or superuser status helps.