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by brianwawok 2230 days ago
If you do stuff like drop columns, you totally need to do a vacuum full or you are never getting back disk space...
1 comments

Actually, you should avoid using vacuum full at all. What that operation does is creating a new table with contents of an old table then deleting the old one. This operation is also requesting an exclusive lock, so any write query will cause lockup.

Another problem is that vacuum full compacts the database, it reduces database size on disk, but doesn't mean it makes database faster, often it might actually reduce performance.

Vacuum full might be useful in scenarios where you want to reclaim space, because autovacuum was not tuned correctly and tables get out of hand, if you need to run vacuum full frequently you should tune autovacuum to run more frequently.

Getting back space is real important. Otherwise you have runaway table growth that never ends.

Not saying do it all the time, but it is important to use surgically. You can easily calculate wasted table space

https://www.citusdata.com/blog/2017/10/20/monitoring-your-bl...

When it gets to be too big, it's a good time to do a vacuum full. I normally do it a few times a year on a few giant tables. Yes it locks up a table for a few minutes, but it is a big win and totally worth it.

I'm not denying that VACUUM FULL is useful when things are out of hand. What I'm trying to say is that you probably don't have autovacuum tuned to run often enough (this is also what your link suggests)