Re: Table space not returned to the OS ?

Hello Florents,

Le lun. 27 juin 2022 à 11:30, Florents Tselai <florents(dot)tselai(at)gmail(dot)com> a
écrit :

> Hi,
>
> A few months back (October) I had upgraded a Postgres instance from v12 —>
> 14.
>
> The database disk size under /var/lib/postgresql/12 was around 800GB+ back
> then.
> Note, that IIRC I had used hard-linking during the upgrade.
>
> In the database itself, lots of things have changed since.
> In fact, that database itself has been dropped at some point and restored
> from a backup.
>
> As I was running out of disk space, I started investigating and found out
> that
>
> /var/lib/postgresql/12/main/base/16385 —> 886GB+
> /var/lib/postgresql/14 —> 400GB
>
Can you check if your upgrade process has used hard links between the 2
folders, as explained here:
https://dba.stackexchange.com/a/289007/98943

>
> The last modification date on that directory (../12/) appears to be around
> a month ago,
> When the table with relied 16385 was in fact dropped.
>
> Now, In my update scripts (I use this db as an OLAP) I occasionally run
> VACUUM.
>
> Is it weird that the 886GB space hasn’t been returned to the OS yet?
>
> What’s the safest way to return it to the OS manually?
>
> Thanks
>
>
>
>