Q:

In Redshift, how do you add multiple constraints to a table after creating the table?

In Redshift, is there a way to add multiple constraint to an already created table?
Step ONE, created the table (say month ago)
CREATE TABLE test_user 
(
account_id          BIGINT DEFAULT NULL encode mostly32,
ingest_timestamp    BIGINT DEFAULT NULL ENCODE mostly32,
ingest_date         TIMESTAMP DEFAULT NULL ENCODE delta32k,
user_id             BIGINT NOT NULL encode mostly32,
group_id            BIGINT NOT NULL encode mostly32,
department_id       BIGINT NOT NULL encode mostly32,
name                VARCHAR(255) DEFAULT NULL ENCODE LZO,
mobile              VARCHAR(15) DEFAULT NULL ENCODE LZO,
phone               VARCHAR(15) DEFAULT NULL ENCODE LZO,
user_language       VARCHAR(15) DEFAULT NULL ENCODE runlength,
deleted             INT DEFAULT NULL ENCODE mostly8,
created_at          TIMESTAMP DEFAULT NULL ENCODE delta32k,
updated_at          TIMESTAMP DEFAULT NULL ENCODE delta32k,
PRIMARY KEY (user_id)
)
sortkey (account_id)

Step TWO, created more tables like 'test_group','test_department'
Step THREE, after a month, I am planning to add multiple constraints to 'test_user' table like this(but in separate query)
ALTER TABLE test_user ADD CONSTRAINT FK_1 FOREIGN KEY (group_id) REFERENCES test_group (group_id); 
ALTER TABLE test_user ADD CONSTRAINT FK_1 FOREIGN KEY (department_id) REFERENCES test_department (department_id); 

The above succeeds.
However, Is there a way to add multiple constraints in single query? 
Tried like this,
option 1 -> ALTER TABLE test_user ADD CONSTRAINT FK_1 FOREIGN KEY (group_id) REFERENCES test_group (group_id),ADD CONSTRAINT FK_1 FOREIGN KEY (department_id) REFERENCES test_department (department_id);
option 2 -> ALTER TABLE test_user ADD CONSTRAINT FK_1 FOREIGN KEY (group_id) REFERENCES test_group (group_id), FK_1 FOREIGN KEY (department_id) REFERENCES test_department (department_id);
But got this error for both case,
An error occurred when executing the SQL command:
ALTER TABLE test_user ADD CONSTRAINT FK_1 FOREIGN KEY (group_id) REFERENCES test_group (group_id), FK_2 FOREIGN KEY (department_id) REFERENCES test_department (department_id); REFERENCES helpdesk_user (user_id)

ERROR: syntax error at or near "FK_2"

Is there a way to add multiple constraint to an already created table?
Please help

A:

It doesn't matter when you define them, or even if you define them at all.  
Redshift ignores constraints. Defining them has no effect, except that the optimizer may use them as additional information when creating the access plan.
However, I have created and used massive (billions of rows) databases in redshift, and I didn't define a single constraint of any kind and it all ran amazingly fast.
Answer: Don't bother.

