I think I'm missing something when it comes to grant alter table. I'm looking at the AWS docs
https://docs.aws.amazon.com/redshift/latest/dg/r_GRANT.html
And they say I can grant alter table to a role. I've tried running grant alter table to user but that gives me SQL Error [0LP01]: ERROR: Grant/Revoke system privilege on User is not supported.. So, I'm confused on what exactly a role in redshift is and how it works. Using rows, could I grant a group of people alter table permissions on a single schema?