Re: PostgreSQL reclaiming table space

Anthony Bull <antsbull@gmail.com> writes:
> About 3 hours after the Vacuum full completed, the disk space got returned
> to the OS - now Windows is reporting it has all that disk back.  Must have
> been waiting for something?  Anyway, great news!

Probably means that some session was holding on to an open-file pointer
to the old copy of the table.  It's difficult to ensure that such
pointers are released quickly without causing performance degradation
for normal cases.  (But having said that, I think we've fixed some bugs
in which pointers were held open unnecessarily.  You didn't say exactly
how old a PG version you were using ...)

            regards, tom lane