Greenplum+Hadoop学习笔记-14-定义数据库对象之创建与管理模式

6.3.创建与管理模式

概述：DB内组织对象的一种逻辑结构。一个DB内能够有多个模式。在未指定模式时默认放置在public中。能够通过”\dn”方式查看数据库中现有模式；

testdw=# \dn List of schemas Name | Owner --------------------+--------- gp_toolkit | gpadmin information_schema | gpadmin pg_aoseg | gpadmin pg_bitmapindex | gpadmin pg_catalog | gpadmin pg_toast | gpadmin public | gpadmin (7 rows)

创建模式：使用CREATESCHEMA命令。通过查看帮助例如以下所看到的：

testdw=# \h CREATE SCHEMA Command: CREATE SCHEMA Description: define a new schema Syntax: CREATE SCHEMA schemaname [ AUTHORIZATION username ] [ schema_element [ ... ] ] 将全部者设置为其它角色通过AUTHORIZTION CREATE SCHEMA AUTHORIZATION username [ schema_element [ ... ] ]

訪问模式的对象：schema.table

testdw=# CREATE SCHEMA sc01; CREATE SCHEMA testdw=# \dn List of schemas Name | Owner --------------------+--------- gp_toolkit | gpadmin information_schema | gpadmin pg_aoseg | gpadmin pg_bitmapindex | gpadmin pg_catalog | gpadmin pg_toast | gpadmin public | gpadmin sc01 | gpadmin (8 rows) testdw=# create schema sc02 authorization mavshuang; ERROR: permission denied for database testdw (seg1 slave2:40000 pid=5424) 提示testdw数据库中权限拒绝 testdw=# grant all on database testdw to mavshuang; 将testdw数据库的全部权限赋给mavshuang GRANT testdw=# create schema sc02 authorization mavshuang; CREATE SCHEMA testdw=# \dn List of schemas Name | Owner --------------------+----------- gp_toolkit | gpadmin information_schema | gpadmin pg_aoseg | gpadmin pg_bitmapindex | gpadmin pg_catalog | gpadmin pg_toast | gpadmin public | gpadmin sc01 | gpadmin sc02 | mavshuang 此时用户是mavshuang (9 rows)

模式搜索路径：若不想通过指定模式名称的方式来搜索须要的对象。能够通过设置search_path的方式来实现，第一个模式为缺省。

testdw=# show search_path; search_path ---------------- "$user",public (1 row)

通过ALTERDATABASE改动DB的模式搜索路径

testdw-# \h alter database Command: ALTER DATABASE Description: change a database Syntax: ALTER DATABASE name [ [ WITH ] option [ ... ] ] where option can be: CONNECTION LIMIT connlimit ALTER DATABASE name SET parameter { TO | = } { value | DEFAULT } 通过此命令来改动DB的模式搜索路径 ALTER DATABASE name RESET parameter ALTER DATABASE name RENAME TO newname ALTER DATABASE name OWNER TO new_owner

testdw=# alter database testdw set search_path to sc01,public,pg_catalog; 设置testdw数据库的搜索路径为sc01,public,pg_catalog; ALTER DATABASE testdw=# \q 改动完毕后通过\q退出testdw数据库后又一次登录 [gpadmin@master ~]$ psql -d testdw psql (8.2.15) Type "help" for help. testdw=# show search_path; search_path -------------------------- sc01, public, pg_catalog (1 row)

通过ALTER ROLE改动ROLE(User)的模式搜索路径：

testdw-# \h alter role Command: ALTER ROLE Description: change a database role Syntax: ALTER ROLE name RENAME TO newname ALTER ROLE name SET config_parameter {TO | =} {value | DEFAULT} ALTER ROLE name RESET config_parameter ALTER ROLE name RESOURCE QUEUE {queue_name | NONE} ALTER ROLE name [ [WITH] option [ ... ] ] where option can be: SUPERUSER | NOSUPERUSER | CREATEDB | NOCREATEDB | CREATEROLE | NOCREATEROLE | CREATEEXTTABLE | NOCREATEEXTTABLE [ ( attribute='value'[, ...] ) ] where attributes and values are: type='readable'|'writable' protocol='gpfdist'|'http'|'gphdfs' | INHERIT | NOINHERIT | LOGIN | NOLOGIN | CONNECTION LIMIT connlimit | [ENCRYPTED | UNENCRYPTED] PASSWORD 'password' | VALID UNTIL 'timestamp'

testdw=# select * from pg_roles; 查询pg_roles字典表 rolname | rolsuper | rolinherit | rolcreaterole | rolcreatedb | rolcatupdate | rolcanlogin | rolconnlimit | rolpassword | rolvaliduntil | rolconfig | rolresqueue | oid | rolcreaterextgpfd | rolcreaterexthttp | rolcreatewextgpfd | rolcreaterexthdfs | olcreatewexthdfs -----------+----------+------------+---------------+-------------+--------------+-------------+--------------+-------------+---------------+-----------+-------------+-------+-------------------+-------------------+-------------------+-------------------+- ----------------- mavshuang | f | t | f | f | f | t | -1 | ******** | | | 6055 | 16384 | f | f | f | f | admin | f | t | t | t | f | f | -1 | ******** | | | 6055 | 16385 | f | f | f | f | gpadmin | t | t | t | t | t | t | -1 | ******** | | | 6055 | 10 | t | t | t | t | (3 rows) testdw=# alter role mavshuang set search_path to public,sc01,pg_catalog; 改动mavshuang角色的搜索路径为public,sc01,pg_catalog; ALTER ROLE testdw=# select * from pg_roles; 再次查询显示 rolname | rolsuper | rolinherit | rolcreaterole | rolcreatedb | rolcatupdate | rolcanlogin | rolconnlimit | rolpassword | rolvaliduntil | rolconfig | rolresqueue | oid | rolcreaterextgpfd | rolcreaterexthttp | rolcreate extgpfd | rolcreaterexthdfs | rolcreatewexthdfs -----------+----------+------------+---------------+-------------+--------------+-------------+--------------+-------------+---------------+------------------------------------------+-------------+-------+-------------------+-------------------+---------- --------+-------------------+------------------- admin | f | t | t | t | f | f | -1 | ******** | | | 6055 | 16385 | f | f | f | f | f gpadmin | t | t | t | t | t | t | -1 | ******** | | | 6055 | 10 | t | t | t | t | t mavshuang | f | t | f | f | f | t | -1 | ******** | | {"search_path=public, sc01, pg_catalog"} | 6055 | 16384 | f | f | f | f | f (3 rows)

查看当前的模式：通过current_schema()函数或者SHOW命令来查看：

testdw=# select current_schema(); 仅仅能显示一个模式 current_schema ---------------- sc01 (1 row) testdw=# show search_path; 显示当前数据库全部的模式 search_path -------------------------- sc01, public, pg_catalog (1 row)

删除模式：使用DROPSCHEMA命令(空模式)

testdw=# \h drop schema Command: DROP SCHEMA Description: remove a schema Syntax: DROP SCHEMA [ IF EXISTS ] name [, ...] [ CASCADE | RESTRICT ] 当该模式下有对象时能够使用CASCADE命令 testdw=# drop schema sc01; DROP SCHEMA

系统模式

pg_catalog模式存储系统日志表.内置类型.函数和运算符。

Information_schem模式由一个标准化视图构成。

当中包括DB中对象的信息。

pg_toast模式是存储大对象(系统内部使用)

pg_bitmapindex模式存储bitmap index对象(系统内部使用)

pg_aoseg存储append-only表(系统内部使用)

gp_toolkit是管理用的模式，能够查看和检索系统日志文件和其它系统信息。