Re: Recommendation to run vacuum FULL in parallel

> Does *every* table have *so much* free space that it's impractical to 
> just
> let the files just get refilled by normal usage?
>
Ideally VACUUM FULL should not require a giant lock on the table.

Sometimes a table's usage pattern involves much more updates than 
inserts, which gradually uses more and more unused space that is never 
used again by postgres, and plain autovacuuming doesn't return it to the 
OS. So DB size (as witnessed by psql's \l+) uses 5-6x times the space it 
actually needs. And using vacuum full is prohibitive because of the 
exclusive lock it takes on the table, preventing both writes and reads. 
Since rewriting a table is a completely internal operation from clients' 
POV, hopefully one day we will see a concurrent version of vacuum full.