Can't create read-write Postgresql user I'm trying to create two users in a Postgres database—one with read-write access to all tables in two schemas, and one with read-write-create (i.e., able to make DDL changes) to the same schemas.

I currently have these statements.

CREATE SCHEMA
    schema_a;

CREATE SCHEMA
    schema_b;

CREATE ROLE read;
CREATE ROLE read_write;
CREATE ROLE read_write_create;

GRANT USAGE ON SCHEMA schema_a, schema_b TO read;
GRANT SELECT ON ALL TABLES IN SCHEMA schema_a, schema_b TO read;

GRANT INSERT, UPDATE, DELETE ON ALL TABLES IN SCHEMA schema_a, schema_b TO read_write;
GRANT USAGE, SELECT ON ALL SEQUENCES IN SCHEMA schema_a, schema_b TO read_write;

GRANT ALL ON SCHEMA schema_a, schema_b TO read_write_create;

GRANT read to read_write;
GRANT read_write to read_write_create;

ALTER DEFAULT PRIVILEGES IN SCHEMA schema_a, schema_b GRANT SELECT ON TABLES TO read;
ALTER DEFAULT PRIVILEGES IN SCHEMA schema_a, schema_b GRANT SELECT ON SEQUENCES TO read;
ALTER DEFAULT PRIVILEGES IN SCHEMA schema_a, schema_b GRANT INSERT, UPDATE, DELETE ON TABLES TO read_write;
ALTER DEFAULT PRIVILEGES IN SCHEMA schema_a, schema_b GRANT SELECT, UPDATE ON SEQUENCES TO read_write;

CREATE USER
    read_write_user
WITH PASSWORD
    'a_password';

GRANT read_write TO read_write_user;

CREATE USER
    read_write_create_user
WITH PASSWORD
    'another_password';

GRANT read_write_create TO read_write_create_user;


After running these, read_write_create_user can create tables, read from, and write to all tables. But read_write_user can't read or write to any tables created by read_write_create_user.

What am I doing wrong?
This is because the tables in either schema are created by a different role (I assume read_write_create_user) than the one the default privileges were defined for (which is you, or the role that run the above set of statements).

You'll find a bit more explanation in my older answer.