openGauss每日一练第12天 | 学习心得体会（schma的创建、重命名，搜索顺序设置）

学习目标

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。

实验环境

omm=# \l
                          List of databases
   Name    | Owner  | Encoding | Collate | Ctype | Access privileges 
-----------+--------+----------+---------+-------+-------------------
 mydb      | myuser | UTF8     | C       | C     | 
 omm       | omm    | UTF8     | C       | C     | 
 postgres  | omm    | UTF8     | C       | C     | 
 template0 | omm    | UTF8     | C       | C     | =c/omm           +
           |        |          |         |       | omm=CTc/omm
 template1 | omm    | UTF8     | C       | C     | =c/omm           +
           |        |          |         |       | omm=CTc/omm
(5 rows)
omm=# \db
          List of tablespaces
    Name    | Owner |     Location      
------------+-------+-------------------
 app_ts     | omm   | tablespace/appts
 enmtbs     | omm   | tablespace/enmtbs
 pg_default | omm   | 
 pg_global  | omm   | 
(4 rows)

omm=# \dn
     List of schemas
      Name       | Owner  
-----------------+--------
 blockchain      | omm
 cstore          | omm
 db4ai           | omm
 dbe_perf        | omm
 dbe_pldebugger  | omm
 dbe_pldeveloper | omm
 jack            | jack
 myuser          | myuser
 pkg_service     | omm
 public          | omm
 snapshot        | omm
 sqladvisor      | omm
 test            | test
(13 rows)

omm=# 
omm=# \du
                                                              List of roles
 Role name |                                                    Attributes                                                    | Member of 
-----------+------------------------------------------------------------------------------------------------------------------+-----------
 gaussdb   | Sysadmin                                                                                                         | {}
 jack      |                                                                                                                  | {}
 myuser    | Sysadmin                                                                                                         | {}
 omm       | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyadmin, UseFT | {}
 test      | 

课后练习

1.创建一个名为testsm、testsm1的模式

omm=# create schema testsm AUTHORIZATION myuser;
CREATE SCHEMA
omm=# create schema testsm1 AUTHORIZATION myuser;
CREATE SCHEMA

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

-- 创建用户
omm=# create user john identified by 'kunpeng@1234';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
-- 查看testsm为myuser
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
 myuser          | myuser |                   |                                  | f
 pkg_service     | omm    |                   | pkg_service schema               | f
 public          | omm    | omm=UC/omm       +| standard public schema           | f
                 |        | =U/omm            |                                  | 
 dbe_pldeveloper | omm    | omm=UC/omm       +| dbe_pldeveloper schema           | f
                 |        | =U/omm            |                                  | 
 jack            | jack   |                   |                                  | f
                 |        | =U/omm            |                                  | 
 test            | test   |                   |                                  | f
 testsm          | myuser |                   |                                  | f
--More-- snapshot        | omm    |                   | snapshot schema                  | f
 sqladvisor      | omm    | omm=UC/omm       +| sqladvisor schema                | f
 testsm1         | myuser |                   |                                  | f
(16 rows)

-- 修改schema的拥有者为john                            ^
omm=# alter user john SYSADMIN;
ALTER ROLE
omm=# alter schema testsm owner to john;
ALTER SCHEMA
--再次查看testsm为john
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
 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            |                                  | 
 test            | test   |                   |                                  | f
 testsm          | john   |                   |                                  | f
--More--                 |        | =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            |                                  | 
 jack            | jack   |                   |                                  | f
 john            | john   |                   |                                  | f
 myuser          | myuser |                   |                                  | f
 testsm1         | myuser |                   |                                  | f
(16 rows)

omm=# 

3.重命名testsm为testsm2 (使用 rename to 就对了)

omm=# alter schema testsm rename to testsm2;
ALTER SCHEMA

4.在模式testsm1中建表t1、插入记录和查询记录

omm=# create table testsm1.t1(a int);
CREATE TABLE
omm=# insert into testsm1.t1 values (1);
INSERT 0 1
omm=# select * from testsm1.t1;
 a 
---
 1
(1 row)

5.在会话级设置模式搜索顺序(只对当前会话生效）

omm=# set SEARCH_PATH TO testsm1;
SET
omm=# show SEARCH_PATH;
 search_path 
-------------
 testsm1
(1 row)

omm=# 
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

omm=# alter database mydb set SEARCH_PATH TO testsm1;
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=# \c mydb myuser
Password for user myuser: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "mydb" as user "myuser".
mydb=> 
mydb=> show SEARCH_PATH;
 search_path 
-------------
 testsm1
(1 row)

mydb=> 

7.在用户级设置模式搜索顺序

mydb=> 
mydb=> ALTER USER myuser SET SEARCH_PATH TO TESTSM2;
ALTER ROLE
mydb=> \q
omm@modb:~$ gsql -d mydb -U myuser -W kunpeng@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.

mydb=> show SEARCH_PATH;
 search_path 
-------------
 testsm2
(1 row)

mydb=> 

21天打卡，坚持坚持再坚持，加油！！！