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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: ð
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: ð
set maintenance_work_mem = '256MB'; ð
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 |
