list of schema with sizes (relative and absolute) in a PostgreSQL database

Question

I\'m looking for a query that returns a result of the form for any database (see example below supposing total space used by the database is 40GB)

schema | si         


        

Answer 1

https://www.depesz.com/2018/02/17/which-schema-is-using-the-most-disk-space/

shows a solution that counts the TOAST tabels as well. Tested on PG12:

 WITH recursive all_elements AS (
    SELECT 'base/' || l.filename AS path, x.*
    FROM
        pg_ls_dir('base/') AS l (filename),
        LATERAL pg_stat_file( 'base/' || l.filename) AS x
    UNION ALL
    SELECT 'pg_tblspc/' || l.filename AS path, x.*
    FROM
        pg_ls_dir('pg_tblspc/') AS l (filename),
        LATERAL pg_stat_file( 'pg_tblspc/' || l.filename) AS x
    UNION ALL
    SELECT
        u.path || '/' || l.filename, x.*
    FROM
        all_elements u,
        lateral pg_ls_dir(u.path) AS l(filename),
        lateral pg_stat_file( u.path || '/' || l.filename ) AS x
    WHERE
        u.isdir
), all_files AS (
    SELECT path, SIZE FROM all_elements WHERE NOT isdir
), interesting_files AS (
    SELECT
        regexp_replace(
            regexp_replace(f.path, '.*/', ''),
            '\.[0-9]*$',
            ''
        ) AS filename,
        SUM( f.size )
    FROM
        pg_database d,
        all_files f
    WHERE
        d.datname = current_database() AND
        f.path ~ ( '/' || d.oid || E'/[0-9]+(\\.[0-9]+)?$' )
    GROUP BY filename
)
SELECT
    n.nspname AS schema_name,
    SUM( f.sum ) AS total_schema_size
FROM
    interesting_files f
    JOIN pg_class c ON f.filename::oid = c.relfilenode
    LEFT OUTER JOIN pg_class dtc ON dtc.reltoastrelid = c.oid AND c.relkind = 't'
    JOIN pg_namespace n ON COALESCE( dtc.relnamespace, c.relnamespace ) = n.oid
GROUP BY
    n.nspname
ORDER BY
    total_schema_size DESC