select pg_size_pretty(pg_database_size('lrisk')); --查询数据库剩余空间
select pg_database.datname,pg_size_pretty(pg_database_size('lrisk')) AS size
from pg_database;
select * from pg_database;
SELECT relname, relpages FROM pg_class ORDER BY relpages DESC; --查询数据库对象占用空间从大到小排序