Re: Available disk space per tablespace

Hi,

I also tested the patch on Linux mint 22.1 with the btrfs and ext4
partitions. I generated some data and the outcome looks good:

postgres=# \db+
                                                   List of tablespaces
       Name       |  Owner   |         Location          | Access
privileges | Options |  Size   |  Free   | Description
------------------+----------+---------------------------+-------------------+---------+---------+---------+-------------
 pg_default       | postgres | |                   |         | 1972 MB
| 29 GB   |
 pg_global        | postgres | |                   |         | 556 kB 
| 29 GB   |
 tablespace_test2 | postgres | /media/said/queryme/pgsql
|                   |         | 3147 MB | 1736 GB |

Numbers are the same as if I were executing the command: df -h

tablespace_test2 was the ext4 partition on usb stick.

Numbers are correct.

Said

On 2025-03-13 14 h 10, Christoph Berg wrote:
> Hi,
>
> I'm picking up a 5 year old patch again:
> https://www.postgresql.org/message-id/flat/20191108132419.GG8017%40msg.df7cb.de
>
> Users will be interested in knowing how much extra data they can load
> into a database, but PG currently does not expose that number. This
> patch introduces a new function pg_tablespace_avail() that takes a
> tablespace name or oid, and returns the number of bytes "available"
> there. This is the number without any reserved blocks (Unix, f_avail)
> or available to the current user (Windows).
>
> (This is not meant to replace a full-fledged OS monitoring system that
> has much more numbers about disks and everything, it is filling a UX
> gap.)
>
> Compared to the last patch, this just returns a single number so it's
> easier to use - total space isn't all that interesting, we just return
> the number the user wants.
>
> The free space is included in \db+ output:
>
> postgres =# \db+
> List of tablespaces
> Name │ Owner │ Location │ Access privileges │ Options │ Size │ Free │ Description
> ────────────┼───────┼──────────┼───────────────────┼─────────┼─────────┼────────┼─────────────
> pg_default │ myon │ │ ∅ │ ∅ │ 23 MB │ 538 GB │ ∅
> pg_global │ myon │ │ ∅ │ ∅ │ 556 kB │ 538 GB │ ∅
> spc │ myon │ /tmp/spc │ ∅ │ ∅ │ 0 bytes │ 31 GB │ ∅
> (3 rows)
>
> The patch has also been tested on Windows.
>
> TODO: Figure out which systems need statfs() vs statvfs()
>
> Christoph