查看数据库的大小：

​
SELECT d.datname as "Name",
       pg_catalog.pg_get_userbyid(d.datdba) as "Owner",
       pg_catalog.pg_encoding_to_char(d.encoding) as "Encoding",
       d.datcollate as "Collate",
       d.datctype as "Ctype",
       pg_catalog.array_to_string(d.datacl, E'\n') AS "Access privileges",
       CASE WHEN pg_catalog.has_database_privilege(d.datname, 'CONNECT')
            THEN pg_catalog.pg_size_pretty(pg_catalog.pg_database_size(d.datname))
            ELSE 'No Access'
       END as "Size",
       t.spcname as "Tablespace",
       pg_catalog.shobj_description(d.oid, 'pg_database') as "Description"
FROM pg_catalog.pg_database d
  JOIN pg_catalog.pg_tablespace t on d.dattablespace = t.oid
ORDER BY 1;

​

查看表的大小：

SELECT
	t.table_catalog as db,
	n.nspname AS schemaname,
	c.relname,
	c.reltuples::numeric as rowcount,
	pg_size_pretty(pg_table_size ( '"' || nspname || '"."' || relname || '"' )) AS table_size,
    pg_size_pretty(pg_indexes_size ( '"' || nspname || '"."' || relname || '"' )) AS indexes_size,
	pg_size_pretty (pg_total_relation_size ( '"' || nspname || '"."' || relname || '"' )) AS total_size --,pg_relation_filepath(table_name) filepath
FROM pg_class C 
	LEFT JOIN pg_namespace N ON ( N.oid = C.relnamespace ) 
	left join information_schema.tables t on (n.nspname= t.table_schema and c.relname=t."table_name" )
WHERE
	nspname NOT IN ( 'pg_catalog', 'information_schema' ) 
	AND relkind in ('r','p')  
ORDER BY
	reltuples DESC 
	LIMIT 20;