I have 2 identical systems A + B. B being a clone of A.
The table pg_catalog.pg_largeobject was identical on both systems: 300GB in total size; 100GB bloated. I did following on A: ? vacuum full pg_catalog.pg_largeobject; (using the default maintenance_work_mem of 64MB) It took around 45 minutes and increased the diskspace by around 125% until the vacuum had been finished. I did following on B: ? set maintenance_work_mem = '256MB'; ? vacuum full pg_catalog.pg_largeobject; This took around 5 minutes. I don't know if the diskspace ever increased. I was really surprised. Is there any explanation on this behavior? Is vacuum full heavily using on-disk sort areas if maintenance_work_mem is too low? Postgres Version 9.6 Thanks, Markus
