参考用pg_table_size(regclass)函数：
select tablename,
pg_size_pretty(pg_table_size( (quote_ident(schemaname) || '.' || quote_ident(tablename))::regclass ))
from pg_tables
order by tablename;

也可以：
select relname, pg_size_pretty(pg_table_size(oid)) from pg_class
where relkind = 'r'
order by relname;

或者：
SELECT RELNAME ,pg_relation_size(RELNAME::regclass )  FROM PG_STAT_USER_TABLES ;
relname | pg_relation_size
---------+------------------
foo     |        217489408
(1 row)

请自行参考，写你自己的sql语句。

加我私人微信，交流技术。