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；
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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：
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testdw=# \h CREATE SCHEMA Command: CREATE SCHEMA Description: define a new schema Syntax: CREATE SCHEMA schemaname [ AUTHORIZATION username ] [ schema_element [ ... ] ] CREATE SCHEMA AUTHORIZATION username [ schema_element [ ... ] ] |
- 訪问模式的对象：schema.table
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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) testdw=# grant all on database testdw to 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 (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。
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testdw=# show search_path; search_path ---------------- "$user",public (1 row) |
- 通过ALTERDATABASE改动DB的模式搜索路径
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testdw-# \h alter database Command: ALTER DATABASE Description: change a database Syntax: ALTER DATABASE name [ [ WITH ] option [ ... ] ] where option can be: CONNECTION LIMIT connlimit ALTER DATABASE name SET parameter { TO | = } { value | DEFAULT } ALTER DATABASE name RESET parameter ALTER DATABASE name RENAME TO newname ALTER DATABASE name OWNER TO new_owner |
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testdw=# alter database testdw set search_path to sc01,public,pg_catalog; 设置testdw数据库的搜索路径为sc01,public,pg_catalog; ALTER DATABASE testdw=# \q 改动完毕后通过\q退出testdw数据库后又一次登录 [gpadmin@master ~]$ 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：
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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' |
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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; ALTER ROLE testdw=# select * from pg_roles; 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 | ******** | | | 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：
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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)
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testdw=# \h drop schema Command: DROP SCHEMA Description: remove a schema Syntax: DROP SCHEMA [ IF EXISTS ] name [, ...] [ CASCADE | RESTRICT ] 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。