title: Amazon Redshift at 100% disk usage due to VACUUM query
body: <p>Reading the Amazon Redshift documentatoin I ran a VACUUM on a certain 400GB table which has never been vacuumed before, in attempt to improve query performance.
  Unfortunately, the VACUUM has caused the table to grow to 1.7TB (!!) and has brought the Redshift's disk usage to 100%.
  I then tried to stop the VACUUM by running a CANCEL query in the super user queue (you enter it by running "set query_group='superuser';") but although the query didn't raise an error, this had no effect on the vaccum query which keeps running.</p>
  
  <p>What can I do?</p>