SELECT nspname || '.' || relname AS "relation",
    pg_size_pretty(pg_total_relation_size(C.oid)) AS "total_size"
  FROM pg_class C
  LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace)
  WHERE nspname NOT IN ('pg_catalog', 'information_schema')
    AND C.relkind <> 'i'
    AND nspname !~ '^pg_toast'
  ORDER BY pg_total_relation_size(C.oid) DESC
  ;

信贷: https://makandracards.com/makandra/52141-postgresql-how-to-show-table-sizes

SELECT
   relname as "Table",
   pg_size_pretty(pg_total_relation_size(relid)) As "Size",
   pg_size_pretty(pg_total_relation_size(relid) - pg_relation_size(relid)) as "External Size"
   FROM pg_catalog.pg_statio_user_tables ORDER BY pg_total_relation_size(relid) DESC;

从这里截取https://wiki-bsse.ethz.ch/display/ITDOC/Check+size+of+tables+and+objects+in+PostgreSQL+database

SELECT nspname || '.' || relname AS "relation",
    pg_size_pretty(pg_total_relation_size(C.oid)) AS "total_size"
  FROM pg_class C
  LEFT JOIN pg_namespace N ON (N.oid = C.relnamespace)
  WHERE nspname NOT IN ('pg_catalog', 'information_schema')
    AND C.relkind <> 'i'
    AND nspname !~ '^pg_toast'
  ORDER BY pg_total_relation_size(C.oid) DESC
  ;

信贷: https://makandracards.com/makandra/52141-postgresql-how-to-show-table-sizes

如果你正在寻找一个总的分解，吐司和索引大小使用这个:

SELECT *, pg_size_pretty(total_bytes) AS total
, pg_size_pretty(index_bytes) AS INDEX
, pg_size_pretty(toast_bytes) AS toast
, pg_size_pretty(table_bytes) AS TABLE
FROM (
SELECT *, total_bytes-index_bytes-COALESCE(toast_bytes,0) AS table_bytes 
FROM (
  SELECT c.oid,nspname AS table_schema, relname AS TABLE_NAME
          , c.reltuples AS row_estimate
          , pg_total_relation_size(c.oid) AS total_bytes
          , pg_indexes_size(c.oid) AS index_bytes
          , pg_total_relation_size(reltoastrelid) AS toast_bytes
      FROM pg_class c
      LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
      WHERE relkind = 'r'
  ) a
) a ORDER BY total_bytes DESC;

select table_name,n_live_tup, pg_size_pretty(pg_relation_size(table_name))
from information_schema.tables
inner join pg_stat_user_tables  on table_name=relname
where table_schema = 'public'
order by 2 desc

另一种替代方法

 select uv.a tablename, pg_size_pretty(uv.b) sizepretty 
 from (select tb.tablename a, pg_table_size('schemaname.'||tb.tablename::text) b 
        from pg_tables tb 
        where tb.schemaname ilike 'schemaname' 
        order by 2 desc
       ) uv