Does Grant on MySQL overwrite previous permissions? I ran the following command per AWS Aurora's documentation to give my user permissions to write to S3: GRANT SELECT INTO S3 ON *.* TO 'user'@'domain-or-ip-address'. Unfortunately, it revoked permissions to do anything, so I couldn't even run a basic select statement on any table. 

So what would be the proper statement to append or add the additional permission to run select into s3 for a user?
Suppose S3 is a table of database DB2, you would

grant insert on DB2.s3 to 'user'@'domain-or-ip-address'


But often you would

grant all on DB2.s3 to 'user'@'domain-or-ip-address'


There is no overwriting, grant modifies existing privileges.