查询表信息

使用系统表pg_tables查询数据库所有表的信息

select * from pg_tables;
-- 查看某个schema下的表信息
select* from pg_tables where schemaname = 'shemaname'

使用函数pg_get_tabledef查询表定义

select * from pg_get_tabledef('shemaname.tablename')

查询表是否做过表分析，执行如下命令会返回每个表最近一次做analyze的时间，没有返回时间的则表示没有做过analyze

select pg_stat_get_last_analyze_time(oid),relname from pg_class where relkind='r'; 

查询public下的表做表分析的时间

select pg_stat_get_last_analyze_time(c.oid),c.relname 
  from pg_class c 
  left join pg_namespace n on c.relnamespace = n.oid 
 where c.relkind='r' and n.nspname='public'
;

查询表大小

查询表的总大小（包含表的索引和数据）

select pg_size_pretty(pg_total_relation_size('schemaname.tablename'));

查询表的数据大小（不包括索引）

select pg_size_pretty(pg_relation_size('schemaname.tablename'));

查询系统中所有表占用空间大小排行

select table_schema || '.' || table_name as table_full_name
      ,pg_size_pretty(pg_total_relation_size('"' || table_schema || '"."' || table_name || '"')) as size 
  from information_schema.tables
 order by pg_total_relation_size('"' || table_schema || '"."' || table_name || '"') desc 
 limit xx;
-- 查看某个schema下表占用空间大小
select table_schema || '.' || table_name as table_full_name
      ,pg_size_pretty(pg_total_relation_size('"' || table_schema || '"."' || table_name || '"')) as size 
  from information_schema.tables
 where table_schema = 'schemaname'
 order by pg_total_relation_size('"' || table_schema || '"."' || table_name || '"') desc 
 limit xx;

查询数据库

通过系统表pg_database查询数据库列表

select datname from pg_database;

查询数据库大小

查询数据库的大小

select datname,pg_size_pretty(pg_database_size(datname)) from pg_database;