title: Postgresql - large delete from 500Gb DB / auto-vacuum?
body: <p>I need to delete around 80% of my 500Gb Postgresql DB.
  I have successfully run a delete command for around 50Gb of rows so far, and paused before proceeding. (This took a long time, perhaps one hour)</p>
  
  <p>I notice that after deleting around 50Gb of data, no extra disk space is freed up, but some memory intensive postgres processes can be observed when I run 'htop'. Am I correct in assuming this is down to dead rows, which need to be vacuumed before the disk space is released?</p>
  
  <p>Second part of this question is, if I am not mistaken about the first part, am I better off deleting all the rows and then allowing auto-vacuum to take place? It appears auto-vacuum (or some other intensive background process) has started by itself before I had a chance to continue my row deletion command list. Do I just proceed or should I gracefully tell it to stop first?</p>