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。