openGauss的模式是对数据库做一个逻辑分割。所有的数据库对象都建立在模式下面。openGauss的模式和用户是弱绑定的，所谓的弱绑定是指虽然创建用户的同时会自动创建一个同名模式，但用户也可以单独创建模式，并且为用户指定其他的模式。
在一个数据库中，可以有多个模式。模式可以把一组对象组织在一起。这样组织机构有多少个应用，我们可以将数据库对象组织成几个模式；组织机构有几个部门，也可以为该部门创建单独的模式。默认情况下，用户将访问数据库的public模式。
学习目标
模式管理包括为数据库创建模式、删除模式、查看和设置模式的搜索路径、查看模式中的信息。
课程学习
实验数据库创建模式、删除模式、查看和设置模式的搜索路径等。
课程作业
1.创建一个名为testsm、testsm1的模式
/*
--创建一个模式testsm、testsm1，并查看当前连接的数据库下有哪些模式：
create schema testsm;
create schema testsm1;
\dn
*/
omm=# create schema testsm;
CREATE SCHEMA
omm=# create schema testsm1;
CREATE SCHEMA
omm=# \dn
List of schemas
Name | Owner
-----------------+--------
blockchain | omm
cstore | omm
db4ai | omm
dbe_perf | omm
dbe_pldebugger | omm
dbe_pldeveloper | omm
pkg_service | omm
public | omm
snapshot | omm
sqladvisor | omm
testsm | omm
testsm1 | omm
(12 rows)
2.创建一个用户john, 并将testsm的owner修改为john，且修改owner前后分别使用\dn+查看模式信息
/*
--创建数据库用户john
DROP USER if exists john;
CREATE USER john IDENTIFIED BY 'meiriyilian@1234';
ALTER USER john SYSADMIN;
\du
--将testsm的owner修改为john
\dn+
alter schema testsm owner to john;
\dn+
*/
omm=# CREATE USER john IDENTIFIED BY 'meiriyilian@1234';
NOTICE: The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# ALTER USER john SYSADMIN;
ALTER ROLE
omm=#
omm=# \du
List of roles
Role name | Attributes
| Member of
-----------+------------------------------------------------------------------------------------------
------------------------+-----------
gaussdb | Sysadmin
| {}
john | Sysadmin
| {}
omm | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatorad
min, Policyadmin, UseFT | {}
omm=# \dn+
List of schemas
Name | Owner | Access privileges | Description | WithBlockChain
-----------------+--------+-------------------+----------------------------------+----------------
blockchain | omm | | blockchain schema | f
cstore | omm | | reserved schema for DELTA tables | f
db4ai | omm | omm=UC/omm +| db4ai schema | f
| | =U/omm | |
dbe_perf | omm | | dbe_perf schema | f
dbe_pldebugger | omm | omm=UC/omm +| dbe_pldebugger schema | f
| | =U/omm | |
dbe_pldeveloper | omm | omm=UC/omm +| dbe_pldeveloper schema | f
| | =U/omm | |
john | john | | | f
pkg_service | omm | | pkg_service schema | f
public | omm | omm=UC/omm +| standard public schema | f
| | =U/omm | |
snapshot | omm | | snapshot schema | f
sqladvisor | omm | omm=UC/omm +| sqladvisor schema | f
| | =U/omm | |
testsm | omm | | | f
testsm1 | omm | | | f
(13 rows)
omm=#
omm=# alter schema testsm owner to john;
ALTER SCHEMA
omm=# \dn+
List of schemas
Name | Owner | Access privileges | Description | WithBlockChain
-----------------+--------+-------------------+----------------------------------+----------------
blockchain | omm | | blockchain schema | f
cstore | omm | | reserved schema for DELTA tables | f
db4ai | omm | omm=UC/omm +| db4ai schema | f
| | =U/omm | |
dbe_perf | omm | | dbe_perf schema | f
dbe_pldebugger | omm | omm=UC/omm +| dbe_pldebugger schema | f
| | =U/omm | |
dbe_pldeveloper | omm | omm=UC/omm +| dbe_pldeveloper schema | f
| | =U/omm | |
john | john | | | f
pkg_service | omm | | pkg_service schema | f
public | omm | omm=UC/omm +| standard public schema | f
| | =U/omm | |
snapshot | omm | | snapshot schema | f
sqladvisor | omm | omm=UC/omm +| sqladvisor schema | f
| | =U/omm | |
testsm | john | | | f
testsm1 | omm | | | f
(13 rows)
3.重命名testsm为testsm2
/*
\dn+
alter schema testsm rename to testsm2;
\dn+
*/
omm=# \dn+
List of schemas
Name | Owner | Access privileges | Description | WithBlockChain
-----------------+--------+-------------------+----------------------------------+----------------
blockchain | omm | | blockchain schema | f
cstore | omm | | reserved schema for DELTA tables | f
db4ai | omm | omm=UC/omm +| db4ai schema | f
| | =U/omm | |
dbe_perf | omm | | dbe_perf schema | f
dbe_pldebugger | omm | omm=UC/omm +| dbe_pldebugger schema | f
| | =U/omm | |
john | john | | | f
pkg_service | omm | | pkg_service schema | f
public | omm | omm=UC/omm +| standard public schema | f
| | =U/omm | |
snapshot | omm | | snapshot schema | f
dbe_pldeveloper | omm | omm=UC/omm +| dbe_pldeveloper schema | f
| | =U/omm | |
sqladvisor | omm | omm=UC/omm +| sqladvisor schema | f
| | =U/omm | |
(15 rows)
testsm | john | | | f
testsm1 | omm | | | f
(13 rows)
omm=# alter schema testsm rename to testsm2;
ALTER SCHEMA
omm=# \dn+
List of schemas
Name | Owner | Access privileges | Description | WithBlockChain
-----------------+--------+-------------------+----------------------------------+----------------
blockchain | omm | | blockchain schema | f
cstore | omm | | reserved schema for DELTA tables | f
db4ai | omm | omm=UC/omm +| db4ai schema | f
| | =U/omm | |
dbe_perf | omm | | dbe_perf schema | f
dbe_pldebugger | omm | omm=UC/omm +| dbe_pldebugger schema | f
| | =U/omm | |
dbe_pldeveloper | omm | omm=UC/omm +| dbe_pldeveloper schema | f
| | =U/omm | |
john | john | | | f
pkg_service | omm | | pkg_service schema | f
public | omm | omm=UC/omm +| standard public schema | f
| | =U/omm | |
snapshot | omm | | snapshot schema | f
sqladvisor | omm | omm=UC/omm +| sqladvisor schema | f
| | =U/omm | |
testsm1 | omm | | | f
testsm2 | john | | | f
(13 rows)
4.在模式testsm1中建表t1、插入记录和查询记录
/*
--在模式testsm1中建表t1、插入记录
create table testsm1.t1(col1 char(100));
select * from testsm1.t1;
insert into testsm1.t1 values('Hello from t1 IN SCHEMA testsm1!');
--查看表中内容：
select * from testsm1.t1;
*/
omm=# create table testsm1.t1(col1 char(100));
CREATE TABLE
omm=# select * from testsm1.t1;
col1
------
(0 rows)
omm=# insert into testsm1.t1 values('Hello from t1 IN SCHEMA testsm1!');
INSERT 0 1
omm=# select * from testsm1.t1;
col1
------------------------------------------------------------------------------------------------------
Hello from t1 IN SCHEMA testsm1!
(1 row)
5.在会话级设置模式搜索顺序
/*
--会话级设置模式搜索顺序
在gsql客户端会话中，执行命令SET SEARCH_PATH TO schemaname可以修改模式搜索路径，但只在gsql客户端会话的持续过程中起作用，一旦退出gsql客户端会话，这个设置就丢失了。重新登录gsql会话将模式搜索路径恢复为默认值"$user",public。
show SEARCH_PATH;
SET SEARCH_PATH TO testsm1;
show SEARCH_PATH;
\q
gsql -r
show SEARCH_PATH;
*/
omm=# show SEARCH_PATH;
search_path
----------------
"$user",public
(1 row)
omm=# SET SEARCH_PATH TO testsm1;
SET
omm=# show SEARCH_PATH;
search_path
-------------
testsm1
(1 row)
omm=# \q
omm@modb:~$ gsql -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.
omm=# show SEARCH_PATH;
search_path
----------------
"$user",public
(1 row)
6.在数据库级设置模式搜索顺序
/*
--数据库级设置模式搜索顺序
--修改数据库级别的搜索顺序后，需要重新登录才改变。
show SEARCH_PATH;
ALTER DATABASE omm SET SEARCH_PATH TO testsm2;
show SEARCH_PATH;
\q
gsql -r
show SEARCH_PATH;
--回到默认
ALTER DATABASE omm SET SEARCH_PATH TO "$user", public;
\q
gsql -r
show SEARCH_PATH;
*/
omm=# show SEARCH_PATH;
search_path
-----------------
"$user", public
(1 row)
omm=# ALTER DATABASE omm SET SEARCH_PATH TO testsm2;
ALTER DATABASE
omm=# show SEARCH_PATH;
search_path
-----------------
"$user", public
(1 row)
omm=# \q
omm@modb:~$ gsql -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.
omm=# show SEARCH_PATH;
search_path
-------------
testsm2
(1 row)
omm=# ALTER DATABASE omm SET SEARCH_PATH TO "$user", public;
ALTER DATABASE
omm=# \q
omm@modb:~$ gsql -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.
omm=# show SEARCH_PATH;
search_path
-----------------
"$user", public
(1 row)
7.在用户级设置模式搜索顺序
/*
--设置数据库的用户user1的模式搜索顺序为模式schm2：
ALTER USER john SET SEARCH_PATH TO testsm2;
\q
gsql -d omm -U john -W meiriyilian@1234 -r
show SEARCH_PATH;
*/
omm=# ALTER USER john SET SEARCH_PATH TO testsm2;
ALTER ROLE
omm=# \q
omm@modb:~$ gsql -d omm -U john -W meiriyilian@1234 -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:00 commit 0 last mr )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.
omm=> show SEARCH_PATH;
search_path
-------------
testsm2
(1 row)
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