Monitoring the available disk space is the topmost thing on the
priority for PostgreSQL operation, yet this metric is not available
from the SQL level.
The attached patch implements a function pg_tablespace_statfs(tblspc)
to report disk space numbers per tablespace:
# select * from pg_tablespace_statfs('pg_default');
blocks │ bfree │ bavail │ files │ ffree
───────────┼──────────┼──────────┼──────────┼──────────
103179564 │ 20829222 │ 20815126 │ 26214400 │ 24426295
Open points:
* should these numbers be converted to bytes?
* the column names currently mirror the statfs() names and should
certainly be improved
* which of these columns add to \db+ output?
* possibly extend this (and \db) to pg_wal
Christoph