Detect orphaned files?

[Krysztophe]

There is a query detecting orphaned files that has slipped into pgstats, and some of you may recognize it:
https://github.com/gleu/pgstats/blob/master/pgreport_queries.h#L136

Of course, there must be a big warning about the danger of blind deleting, but I think it could be another service.
To avoid useless warnings, only report files above a few Mb and older than 24h?

WITH ver AS (
    SELECT
        current_setting('server_version_num') pgversion,
        v::INTEGER / 10000 || '.' || MOD(v::INTEGER, 10000) / 100 AS version
    FROM
        current_setting('server_version_num') v
),
tbl_paths AS (
    SELECT
        tbs.oid AS tbs_oid,
        spcname,
        'pg_tblspc/' || tbs.oid || '/' || (
            SELECT
                dir
            FROM
                pg_ls_dir('pg_tblspc/' || tbs.oid || '/', TRUE, FALSE) dir
            WHERE
                dir LIKE E'PG\\_' || ver.version || E'\\_%') AS tbl_path
    FROM
        pg_tablespace tbs,
        ver
    WHERE
        tbs.spcname NOT IN ('pg_default', 'pg_global')
),
files AS (
    SELECT
        d.oid AS database_oid,
        0 AS tbs_oid,
        'base/' || d.oid AS path,
        file_name AS file_name,
        SUBSTRING(file_name FROM E'[0-9]+') AS base_name
    FROM
        pg_database d,
        pg_ls_dir('base/' || d.oid, TRUE, FALSE) AS file_name
    WHERE
        d.datname = current_database()
    UNION ALL
    SELECT
        d.oid,
        tbp.tbs_oid,
        tbl_path || '/' || d.oid,
        file_name,
        (SUBSTRING(file_name FROM E'[0-9]+')) AS base_name
    FROM
        pg_database d,
        tbl_paths tbp,
        pg_ls_dir(tbp.tbl_path || '/' || d.oid, TRUE, FALSE) AS file_name
    WHERE
        d.datname = current_database()
),
orphans AS (
    SELECT
        tbs_oid,
        base_name,
        file_name,
        current_setting('data_directory') || '/' || path || '/' || file_name AS orphaned_file,
        pg_filenode_relation(tbs_oid, base_name::oid) AS rel_without_pgclass
    FROM
        ver,
        files
        LEFT JOIN pg_class c ON (c.relfilenode::text = files.base_name
                OR (c.oid::text = files.base_name
                    AND c.relfilenode = 0
                    AND c.relname LIKE 'pg_%'))
    WHERE
        c.oid IS NULL
        AND LOWER(file_name)
        NOT LIKE 'pg_%'
)
SELECT
    orphaned_file,
    pg_size_pretty((pg_stat_file(orphaned_file)).size) AS file_size,
    (pg_stat_file(orphaned_file)).modification AS modification_date,
    current_database()
FROM
    orphans
WHERE
    rel_without_pgclass IS NULL