Re: Vacuum Full does not release the disk size space after delete from table

Thank Tom!
We will check it.

On Fri, Nov 2, 2018 at 10:35 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Haozhou Wang <hawang(at)pivotal(dot)io> writes:
> > We meet a corner case that related to the behavior of Vacuum Full.
> > ...
> > If we run both sql scripts on same database in parallel, the "VACUUM FULL
> > a;" will not release the disk space.
>
> I think what's happening is that the delete in script 1 happens after the
> "pg_sleep" in script 2 starts. Then the pg_sleep has an open snapshot
> that could potentially see the deleted rows, so they can't be removed yet.
>
> You could check this theory by changing the vacuum to use VERBOSE, and
> seeing what it says about rows that can't be removed yet.
>
> regards, tom lane
>

--
Regards,
Haozhou