概述

本文档记录openGauss 3.0.0数据库每日一练第12天课程作业，掌握openGauss逻辑结构,模式管理。

课程练习

创建一个名为testsm、testsm1的模式

omm@local:/opt/huawei/tmp [postgres]=#create database musicdb12;
CREATE DATABASE
omm@local:/opt/huawei/tmp [postgres]=#\c musicdb12
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb12" as user "omm".
omm@local:/opt/huawei/tmp [musicdb12]=#create schema testsm;
CREATE SCHEMA
omm@local:/opt/huawei/tmp [musicdb12]=#create schema testsm1;
CREATE SCHEMA
omm@local:/opt/huawei/tmp [musicdb12]=#\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)

创建一个用户john

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

omm@local:/opt/huawei/tmp [musicdb12]=#CREATE USER john with sysadmin IDENTIFIED BY 'zs@123456';
CREATE ROLE
omm@local:/opt/huawei/tmp [musicdb12]=#\dn
     List of schemas
      Name       | Owner 
-----------------+-------
 blockchain      | omm
 cstore          | omm
 db4ai           | omm
 dbe_perf        | omm
 dbe_pldebugger  | omm
 dbe_pldeveloper | omm
 john            | john
 pkg_service     | omm
 public          | omm
 snapshot        | omm
 sqladvisor      | omm
 testsm          | omm
 testsm1         | omm
(13 rows)

omm@local:/opt/huawei/tmp [musicdb12]=#\h alter schema 
Command:     ALTER SCHEMA
Description: change the definition of a schema
Syntax:
ALTER SCHEMA schema_name
    RENAME TO new_name;
ALTER SCHEMA schema_name
    OWNER TO new_owner;
ALTER SCHEMA schema_name {WITH | WITHOUT} BLOCKCHAIN;

omm@local:/opt/huawei/tmp [musicdb12]=#alter schema testsm OWNER TO john;
ALTER SCHEMA
omm@local:/opt/huawei/tmp [musicdb12]=#\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)

重命名testsm为testsm2

omm@local:/opt/huawei/tmp [musicdb12]=#alter schema testsm RENAME TO testsm2;
ALTER SCHEMA
omm@local:/opt/huawei/tmp [musicdb12]=#\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)

在模式testsm1中建表t1、插入记录和查询记录

omm@local:/opt/huawei/tmp [musicdb12]=#create table testsm1.day12(id int,name varchar(20));
CREATE TABLE

omm@local:/opt/huawei/tmp [musicdb12]=#insert into testsm1.day12 values (1,'day12 for opengauss');
INSERT 0 1
omm@local:/opt/huawei/tmp [musicdb12]=#select * from testsm1.day12;
 id |        name         
----+---------------------
  1 | day12 for opengauss
(1 row)

在会话级设置模式搜索顺序

omm@local:/opt/huawei/tmp [musicdb12]=#show search_path;
  search_path   
----------------
 "$user",public
(1 row)

omm@local:/opt/huawei/tmp [musicdb12]=#set search_path to testsm1;
SET
omm@local:/opt/huawei/tmp [musicdb12]=#show search_path;
 search_path 
-------------
 testsm1
(1 row)

omm@local:/opt/huawei/tmp [musicdb12]=#\d
                         List of relations
 Schema  | Name  | Type  | Owner |             Storage              
---------+-------+-------+-------+----------------------------------
 testsm1 | day12 | table | omm   | {orientation=row,compression=no}
(1 row)

在数据库级设置模式搜索顺序

omm@local:/opt/huawei/tmp [musicdb12]=#ALTER DATABASE musicdb12 SET SEARCH_PATH TO schm2;
ALTER DATABASE
omm@local:/opt/huawei/tmp [musicdb12]=#\q
[omm@ogauss1 ~]$ gsql -d postgres -p 15400 -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:34 commit 0 last mr  )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.

omm@local:/opt/huawei/tmp [postgres]=#show search_path;
  search_path   
----------------
 "$user",public
(1 row)

omm@local:/opt/huawei/tmp [postgres]=#\c musicdb12
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb12" as user "omm".
omm@local:/opt/huawei/tmp [musicdb12]=#show search_path;
 search_path 
-------------
 schm2
(1 row)

在用户级设置模式搜索顺序

omm@local:/opt/huawei/tmp [musicdb12]=#\c - john
Password for user john: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb12" as user "john".
john@local:/opt/huawei/tmp [musicdb12]=>show search_path;
 search_path 
-------------
 schm2
(1 row)

john@local:/opt/huawei/tmp [musicdb12]=>ALTER USER john SET SEARCH_PATH TO schm1;
ALTER ROLE
john@local:/opt/huawei/tmp [musicdb12]=>show search_path;
 search_path 
-------------
 schm2
(1 row)

john@local:/opt/huawei/tmp [musicdb12]=>\q
[omm@ogauss1 ~]$ gsql -d postgres -p 15400 -r
gsql ((openGauss 3.0.0 build 02c14696) compiled at 2022-04-01 18:12:34 commit 0 last mr  )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.

omm@local:/opt/huawei/tmp [postgres]=#\c musicdb12
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb12" as user "omm".
omm@local:/opt/huawei/tmp [musicdb12]=#show search_path;
 search_path 
-------------
 schm2
(1 row)

omm@local:/opt/huawei/tmp [musicdb12]=#\c - john
Password for user john: 
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "musicdb12" as user "john".
john@local:/opt/huawei/tmp [musicdb12]=>show search_path;
 search_path 
-------------
 schm1  <========
(1 row)

用户级和数据库级切换search_path均需要退出重进生效。

搜索顺序的优先级

会话级模式搜索顺序的优先级最高，用户级模式搜索顺序的优先级第2，数据库级模式搜索顺序的优先级最低。