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

这里的大多数答案使用pg_size_pretty，这是非常有用的，但如果你想输出一个数值，你可以自己计算

SELECT tab_size /1024 AS size_kb
      ,tab_size /1024 /1024 AS size_mb
      ,tab_size /1024 /1024 / 1024 AS size_gb
      ,tab_size /1024 /1024 / 1024 / 1024 AS size_tb
  FROM 
      (
       SELECT pg_total_relation_size(relid) AS tab_size
         FROM pg_catalog.pg_statio_user_tables
        WHERE schemaname = 'your_schema' 
          AND relname = 'your_table'
      ) AS tabs;

 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

我喜欢以下说法:

SELECT 
  table_name, 
  pg_size_pretty( pg_total_relation_size(quote_ident(table_name))), 
  pg_total_relation_size(quote_ident(table_name))
FROM 
  information_schema.tables
WHERE 
  table_schema = 'public'
ORDER BY 
  pg_total_relation_size(quote_ident(table_name)) DESC

你可以看到总大小在一个漂亮的格式，但它的顺序也是正确的。

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