I've spent some time and finally came up with a working solution.

I will publish it here for future reference.

Solution

First of all, you have three tables (foo_table, bar_table, baz_table) which are pointing to your users table by means of foreign keys (called user_id in all cases). You will need to replace the IDs stored in those columns from id to another_id. Here's how you can do it:

-- We are dropping the foreign key constraint on dependant table (in other case it will prevent us from updating the values)ALTER TABLE foo_table DROP CONSTRAINT fk_e52ffdeea76ed395;-- Then, we're swapping values in foreign key column from id to another_idUPDATE foo_table T SET user_id = (SELECT another_id FROM users WHERE id = T.user_id);-- And finally we're creating new foreign key constraint pointing to the another_id instead of idALTER TABLE foo_table ADD CONSTRAINT fk_e52ffdeea76ed395 FOREIGN KEY (user_id) REFERENCES users (another_id) ON DELETE CASCADE;

You will need to repeat the above queries for each dependent table.

After that, all dependent tables will point to your new another_id column.

In the end we will just need to replace the primary key:

-- 1. Dropping the original primary keyALTER TABLE users DROP CONSTRAINT users_pkey-- 2. Renaming existing index for another_id (optional)ALTER INDEX uniq_1483a5e93414710b RENAME TO users_pkey-- 3. Creating new primary key using existing index for another_idALTER TABLE users ADD PRIMARY KEY USING INDEX users_pkey-- 4. Creating index for old id column (optional)CREATE UNIQUE INDEX users_id ON users (id)-- 5. You can drop the original sequence generator if you won't need itDROP SEQUENCE users_id_seq

You can even drop the original id column if you want to.

I hope it will help someone.