openGauss一个数据库中可以创建多个模式

openGauss一个数据库中可以创建多个模式

润阳RunYang

577人浏览 · 2022-11-30 22:01:08

润阳RunYang · 2022-11-30 22:01:08 发布

1.查看当前数据库下有哪些模式

--进入数据库omm，创建测试用户user07、表空间music_tbs07、数据库musicdb07
[omm@ogdb1 ~]$ gsql -d omm -p 40000 -r
gsql ((openGauss 3.1.0 build 4e931f9a) compiled at 2022-09-29 14:19:24 commit 0 last mr  )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.

omm=# \l
                          List of databases
   Name    | Owner | Encoding  | Collate | Ctype | Access privileges 
-----------+-------+-----------+---------+-------+-------------------
 omm       | omm   | SQL_ASCII | C       | C     | 
 postgres  | omm   | SQL_ASCII | C       | C     | 
 template0 | omm   | SQL_ASCII | C       | C     | =c/omm           +
           |       |           |         |       | omm=CTc/omm
 template1 | omm   | SQL_ASCII | C       | C     | =c/omm           +
           |       |           |         |       | omm=CTc/omm
(4 rows)

--执行下面的SQL语句，创建用户user07,授予user07数据库系统的SYSADMIN权限：
omm=# create user user07 identified by 'aabb@123';
CREATE ROLE
omm=# alter user user07 sysadmin;
ALTER ROLE

--创建测试表空间、测试数据库
omm=# create tablespace music_tbs07 relative location 'tablespace/test_ts07';
CREATE TABLESPACE
omm=# 
omm=# create database musicdb07 with tablespace=music_tbs07;
CREATE DATABASE

--使用用户user07连接到数据库musicdb07，首先查看当前数据库下有哪些模式；
omm=# \q
[omm@ogdb1 ~]$ gsql -d musicdb07 -U user07 -p 40000 -r
Password for user user07: 
gsql ((openGauss 3.1.0 build 4e931f9a) compiled at 2022-09-29 14:19:24 commit 0 last mr  )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.

musicdb07=> \dn
     List of schemas
      Name       | Owner 
-----------------+-------
 blockchain      | omm
 cstore          | omm
 db4ai           | omm
 dbe_perf        | omm
 dbe_pldebugger  | omm
 dbe_pldeveloper | omm
 dbe_sql_util    | omm
 pkg_service     | omm
 public          | omm
 snapshot        | omm
 sqladvisor      | omm
(11 rows)

musicdb07=>

2.然后为数据库musicdb创建4个模式，名称自定义

–用户user07在数据库musicdb07中，创建了4个模式：
musicdb07=> create schema c07schema1 authorization user07;
CREATE SCHEMA
musicdb07=> create  schema c07schema2 authorization user07;
CREATE SCHEMA
musicdb07=> create schema c07schema3 authorization user07;
CREATE SCHEMA
musicdb07=> create schema c07schema4 authorization user07;
CREATE SCHEMA

–查看musicdb07数据库下有哪些模式：

musicdb07=> \dn
     List of schemas
      Name       | Owner  
-----------------+--------
 blockchain      | omm
 c07schema1      | user07
 c07schema2      | user07
 c07schema3      | user07
 c07schema4      | user07
 cstore          | omm
 db4ai           | omm
 dbe_perf        | omm
 dbe_pldebugger  | omm
 dbe_pldeveloper | omm
 dbe_sql_util    | omm
 pkg_service     | omm
 public          | omm
 snapshot        | omm
 sqladvisor      | omm
(15 rows)

–除了可以用gsql的元命令\dn来查看数据库有哪些模式，还可以执行下面的SQL语句，查看某个数据库下有哪些模式：

musicdb07=> select catalog_name, schema_name, schema_owner from information_schema.schemata;
 catalog_name |    schema_name     | schema_owner 
--------------+--------------------+--------------
 musicdb07    | pg_toast           | omm
 musicdb07    | cstore             | omm
 musicdb07    | pkg_service        | omm
 musicdb07    | dbe_perf           | omm
 musicdb07    | snapshot           | omm
 musicdb07    | blockchain         | omm
 musicdb07    | pg_catalog         | omm
 musicdb07    | public             | omm
 musicdb07    | sqladvisor         | omm
 musicdb07    | dbe_pldebugger     | omm
 musicdb07    | dbe_pldeveloper    | omm
 musicdb07    | dbe_sql_util       | omm
 musicdb07    | information_schema | omm
 musicdb07    | db4ai              | omm
 musicdb07    | c07schema1         | user07
 musicdb07    | c07schema2         | user07
 musicdb07    | c07schema3         | user07
 musicdb07    | c07schema4         | user07
(18 rows)

3.在数据库musicdb07的不同的模式下创建同名的表

--在不同模式下，创建相同的表                   
musicdb07=> create table c07schema1.testtab(col varchar(100));
CREATE TABLE
musicdb07=> create table c07schema2.testtab(col varchar(100));
CREATE TABLE
musicdb07=> create table c07schema3.testtab(col varchar(100));
CREATE TABLE
musicdb07=> create table c07schema4.testtab(col varchar(100));
CREATE TABLE

--执行下面的SQL语句，往4个模式中的表testtab分别插入一条数据：
--在同一个数据库下，可以直接使用SchemaName.TableName来指定一个表，可以省略数据库名。
musicdb07=> insert into c07schema1.testtab values('Hello! from schema c07schema1   11111');
INSERT 0 1
musicdb07=> insert into c07schema1.testtab values('Hello! from schema c07schema2   22222');
INSERT 0 1
musicdb07=> insert into c07schema3.testtab values('Hello! from schema c07schema3   33333');
INSERT 0 1
musicdb07=> insert into c07schema4.testtab values('Hello! from schema c07schema4   44444');
INSERT 0 1
musicdb07=> 

--执行下面的SQL语句，查看musicdb07数据库目前有哪些表
--创建视图：
musicdb07=> create or replace view my_tables as select table_catalog, table_schema, table_name, table_type from information_schema.tables where
musicdb07-> table_schema not in ('pg_catalog', 'information_schema', 'dbe_perf');
CREATE VIEW


--查看视图：
musicdb07=> select * from my_tables;
 table_catalog |  table_schema   | table_name | table_type 
---------------+-----------------+------------+------------
 musicdb07     | db4ai           | snapshot   | BASE TABLE
 musicdb07     | dbe_pldeveloper | gs_errors  | BASE TABLE
 musicdb07     | dbe_pldeveloper | gs_source  | BASE TABLE
 musicdb07     | public          | my_tables  | VIEW
 musicdb07     | c07schema4      | testtab    | BASE TABLE
 musicdb07     | c07schema3      | testtab    | BASE TABLE
 musicdb07     | c07schema2      | testtab    | BASE TABLE
 musicdb07     | c07schema1      | testtab    | BASE TABLE
(8 rows)

musicdb07=>

4.访问musicdb数据库下不同模式的同名表

--查看默认的搜索模式的顺序
musicdb07=> show SEARCH_PATH;
  search_path   
----------------
 "$user",public
(1 row)

--访问musicdb07数据库下其他模式的表，需要指定模式名前缀：
musicdb07=> select * from c07schema1.testtab;    
                  col                  
---------------------------------------
 Hello! from schema c07schema1   11111
(1 rows)

musicdb07=>  select * from c07schema2.testtab;  
                  col                  
---------------------------------------
 Hello! from schema c07schema2   22222
(1 row)

musicdb07=>  select * from c07schema3.testtab;  
                  col                  
---------------------------------------
 Hello! from schema c07schema3   33333
(1 row)

musicdb07=>  select * from c07schema4.testtab;  
                  col                  
---------------------------------------
 Hello! from schema c07schema4   44444
(1 row)

5.实验理解：模式是在数据库层面，用户是在实例层面

--登录musicdb07数据库，查看用户和模式
[omm@ogdb1 ~]$ gsql -d musicdb07 -p 40000 -U user07 -r
Password for user user07: 
gsql ((openGauss 3.1.0 build 4e931f9a) compiled at 2022-09-29 14:19:24 commit 0 last mr  )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.

musicdb07=> \du
                                                              List of roles
 Role name |                                                    Attributes                                                    | Member of 
-----------+------------------------------------------------------------------------------------------------------------------+-----------
 omm       | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyadmin, UseFT | {}
 user07    | Sysadmin                                                                                                         | {}

musicdb07=> \dn
     List of schemas
      Name       | Owner  
-----------------+--------
 blockchain      | omm
 c07schema1      | user07
 c07schema2      | user07
 c07schema3      | user07
 c07schema4      | user07
 cstore          | omm
 db4ai           | omm
 dbe_perf        | omm
 dbe_pldebugger  | omm
 dbe_pldeveloper | omm
 dbe_sql_util    | omm
 pkg_service     | omm
 public          | omm
 snapshot        | omm
 sqladvisor      | omm
(15 rows)

musicdb07=> 
--登录omm数据库，查看用户和模式
[omm@ogdb1 ~]$ gsql -d omm -p 40000 -r
gsql ((openGauss 3.1.0 build 4e931f9a) compiled at 2022-09-29 14:19:24 commit 0 last mr  )
Non-SSL connection (SSL connection is recommended when requiring high-security)
Type "help" for help.

omm=# \du
                                                              List of roles
 Role name |                                                    Attributes                                                    | Member of 
-----------+------------------------------------------------------------------------------------------------------------------+-----------
 omm       | Sysadmin, Create role, Create DB, Replication, Administer audit, Monitoradmin, Operatoradmin, Policyadmin, UseFT | {}
 user07    | Sysadmin                                                                                                         | {}

omm=# \dn
     List of schemas
      Name       | Owner  
-----------------+--------
 blockchain      | omm
 cstore          | omm
 db4ai           | omm
 dbe_perf        | omm
 dbe_pldebugger  | omm
 dbe_pldeveloper | omm
 dbe_sql_util    | omm
 pkg_service     | omm
 public          | omm
 snapshot        | omm
 sqladvisor      | omm
 user07          | user07
(12 rows)

--可以看到模式是在数据库层面，用户是在实例层面

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