title: Postgresql Aurora DB freeable_memory
body: <p>I have a question regarding the freeable memory for AWS Aurora Postgres. </p>
  
  <p>We recently wanted to create an index on one of our dbs and the db died and made a failover to the slave which all worked fine. It looks like the freeable memory dropped by the configured 500mb of maintenance_work_mem and by that went to around 800mb of memory - right after that the 32gig instance died.</p>
  
  <p>1) I am wondering if the memory that is freeable is the overall system memory and if a low memory here could invoke the system oom killer on the AWS Aurora instance? So we may want to plan in more head room for operational tasks and the running of autovacuum jobs to not encounter this issue again?</p>
  
  <p>2) The actual work of the index creation should then have used the free local storage as far as I understood, so the size of the index shouldn't have mattered, right?</p>
  
  <p>Thanks in advance,
  Chris</p>