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 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
   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

 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

您可以获得总关系大小和关系大小，这可能取决于您的表关系。 下面是如何获取数据库中的前100个表:

SELECT schemaname                                    AS table_schema,
       relname                                       AS table_name,
       PG_SIZE_PRETTY(PG_TOTAL_RELATION_SIZE(relid)) AS total_size,
       PG_SIZE_PRETTY(PG_RELATION_SIZE(relid))       AS data_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,
         PG_RELATION_SIZE(relid) DESC
LIMIT 100;