PostgreSql 中常用sql

--查看資料庫
select * from pg_database;

--查看錶空間
select * from pg_tablespace;

--查看語言
select * from pg_language;

--查看角色使用者
select * from pg_user;
select * from pg_shadow;
select * from pg_roles;

--查看會話進程
select * from pg_stat_activity;

--查看錶
SELECT * FROM pg_tables where schemaname = 'public';

--查看錶欄位
select * from information_schema.columns where table_schema = 'public' and table_name = 'pf_vip_org';

--查看視圖
select * from pg_views where schemaname = 'public';
select * from information_schema.views where table_schema = 'public';

--查看觸發器
select * from information_schema.triggers;

--查看序列
select * from information_schema.sequences where sequence_schema = 'public';

 --查看約束
select * from pg_constraint where contype = 'p' 

select * from pg_constraint where connamespace=2200 and conrelid=24826
--u unique,p primary,f foreign,c check,t trigger,x exclusion

select a.relname as table_name,b.conname as constraint_name,b.contype as constraint_type from pg_class a,pg_constraint b where a.oid = b.conrelid and a.relname = 'cc';

--查看過程函數（包含觸發器函數和函數）
select oid,* from pg_proc where pronamespace=2200;

--2200為public的oid

 

--查看索引
select * from pg_index ;

--查看錶上存在哪些索引以及大小
select relname,n.amname as index_type from pg_class m,pg_am n where m.relam = n.oid and m.oid in (
select b.indexrelid from pg_class a,pg_index b where a.oid = b.indrelid and a.relname = 'cc');

SELECT c.relname,c2.relname, c2.relpages*8 as size_kb
FROM pg_class c, pg_class c2, pg_index i
WHERE c.relname = 'cc' AND
c.oid = i.indrelid AND
c2.oid = i.indexrelid
ORDER BY c2.relname;

--查看索引定義
select b.indexrelid from pg_class a,pg_index b where a.oid = b.indrelid and a.relname = 'cc';
select pg_get_indexdef(b.indexrelid);

--查看過程函數定義
select oid,* from pg_proc where proname = 'insert_platform_action_exist'; --oid = 24610
select * from pg_get_functiondef(24610);

--查看錶大小(不含索引等資訊)
select pg_relation_size('cc');                         --368640 byte
select pg_size_pretty(pg_relation_size('cc'))   --360 kB

--查看DB大小
select pg_size_pretty(pg_database_size('smiletao'));   --12M

--查看伺服器DB運行狀態
[postgres@eyar ~]$ pg_ctl status -D $PGDATA
pg_ctl: server is running (PID: 2373)
/home/postgres/bin/postgres "-D" "/database/pgdata"

--查看每個DB的使用方式(讀,寫,緩衝,更新,事務等)
select * from pg_stat_database

--查看索引的使用方式
select * from pg_stat_user_indexes;

--查看錶所對應的資料檔案路徑與大小
SELECT pg_relation_filepath(oid), relpages FROM pg_class WHERE relname = 'empsalary';

--查看索引與相關欄位及大小
 SELECT n.nspname AS schema_name,
        r.rolname as table_owner,
       bc.relname AS table_name,
       ic.relname AS index_name,
       a.attname  AS column_name,
       bc.relpages*8 as index_size_kb    
  FROM pg_namespace n,
       pg_class bc,             -- base class
       pg_class ic,             -- index class
       pg_index i,
       pg_attribute a,           -- att in base
       pg_roles r
  WHERE bc.relnamespace = n.oid
     and i.indrelid = bc.oid
     and i.indexrelid = ic.oid
     and bc.relowner = r.oid
     and i.indkey[0] = a.attnum
     and i.indnatts = 1
     and a.attrelid = bc.oid
     and n.nspname = 'public'
     and bc.relname = 'cc'
  ORDER BY schema_name, table_name, index_name, attname;

--查看PG鎖
select * from pg_locks;

備忘：relpages*8 是實際所佔磁碟大小

--查看錶空間大小
select pg_tablespace_size('pg_default');

--查看序列與表的對應關係
  WITH fq_objects AS (SELECT c.oid,c.relname AS fqname ,
                           c.relkind, c.relname AS relation
                    FROM pg_class c JOIN pg_namespace n ON n.oid = c.relnamespace ),

     sequences AS (SELECT oid,fqname FROM fq_objects WHERE relkind = 'S'),
     tables    AS (SELECT oid, fqname FROM fq_objects WHERE relkind = 'r' )
         SELECT
       s.fqname AS sequence,
       '->' as depends,
       t.fqname AS table
      FROM
       pg_depend d JOIN sequences s ON s.oid = d.objid
                 JOIN tables t ON t.oid = d.refobjid
          WHERE
       d.deptype = 'a' and t.fqname = 'cc';

--資料庫分頁查詢---

select ctid,* from kakou_clxx limit 10 offset 10
select ctid,* from kakou_clxx limit 10 offset 20