openGauss每日一练第8天 - 学习心得体会

1.创建表空间newtbs1、 ds_location1，查看表空间

omm=# create tablespace newtbs2 relative location 'tablespace/newtbs1_c2';
CREATE TABLESPACE

omm=# create tablespace ds_location1 relative location 'tablespace/ds_location1';
CREATE TABLESPACE

omm=# create user user1 identified by 'kunpeng@1234';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# alter user user1 sysadmin;
ALTER ROLE

omm=# \db
              List of tablespaces
     Name     | Owner |        Location         
--------------+-------+-------------------------
 ds_location1 | omm   | tablespace/ds_location1
 newtbs1      | omm   | tablespace/newtbs1_c1
 pg_default   | omm   | 
 pg_global    | omm   | 
(4 rows)

2.创建一个数据库newdb1，默认表空间为newtbs1

omm=# create database newdb1 with tablespace = newtbs1;
CREATE DATABASE

3.创建用户user5，并授予SYSADMIN权限，访问数据库newdb1，在表空间ds_location1上，创建一个表newt1（表结构自定义）

omm=# create user user5 identified by 'kunpeng@1234';
NOTICE:  The encrypted password contains MD5 ciphertext, which is not secure.
CREATE ROLE
omm=# alter user user5 sysadmin;
ALTER ROLE

newdb1=# create table newt1 (col char(10)) tablespace  ds_location1;
CREATE TABLE

newdb1=# \d+ newt1
                            Table "public.newt1"
 Column |     Type      | Modifiers | Storage  | Stats target | Description 
--------+---------------+-----------+----------+--------------+-------------
 col    | character(10) |           | extended |              | 
Has OIDs: no
Tablespace: "ds_location1"
Options: orientation=row, compression=no

4.查看表所在的表空间

---pg_tables中查询
newdb1=# select schemaname,tablename ,tablespace,created,last_ddl_time from pg_tables where tename='newt1';
 schemaname | tablename |  tablespace  |            created            |         last_ddl_time  
       
------------+-----------+--------------+-------------------------------+------------------------
-------
 public     | newt1     | ds_location1 | 2022-12-01 11:37:41.892657+08 | 2022-12-01 11:37:41.892
657+08
(1 row)

--使用元命令查询
newdb1=# \d+ newt1
                            Table "public.newt1"
 Column |     Type      | Modifiers | Storage  | Stats target | Description 
--------+---------------+-----------+----------+--------------+-------------
 col    | character(10) |           | extended |              | 
Has OIDs: no
Tablespace: "ds_location1"
Options: orientation=row, compression=no

--

5.查看表空间newtbs1、 ds_location1上的对象

newdb1=# \c newdb1
Non-SSL connection (SSL connection is recommended when requiring high-security)
You are now connected to database "newdb1" as user "omm".
newdb1=# 
select relname, relkind, relpages,pg_size_pretty(pg_relation_size(a.oid)),reltablespace,relowner  
from pg_class a, pg_tablespace tb  
where a.relkind in ('r', 'i')  
and a.reltablespace=tb.oid  
and tb.spcname in('ds_location1' ,'newtbs1')
order by a.relpnewdb1=# ages desc;newdb1-# newdb1-# newdb1-# newdb1-# newdb1-# 
 relname | relkind | relpages | pg_size_pretty | reltablespace | relowner 
---------+---------+----------+----------------+---------------+----------
 newt1   | r       |        0 | 8192 bytes     |         16390 |       10
(1 row)

6. 查看数据库默认的表空间

omm=# select datname,dattablespace,spcname from pg_database d,pg_tablespace t where d.dattablespace=t.oid;
  datname  | dattablespace |  spcname   
-----------+---------------+------------
 template1 |          1663 | pg_default
 omm       |          1663 | pg_default
 newdb1    |         16389 | newtbs1
 template0 |          1663 | pg_default
 postgres  |          1663 | pg_default
(5 rows)

7. 查询默认表空间的表

omm=# \d pg_toast_2618
Did not find any relation named "pg_toast_2618".
omm=# select relname, relkind, relpages,pg_size_pretty(pg_relation_size(a.oid)),reltablespace,relowner  
from pg_class a  
where a.relkind in ('r', 'i')  
and reltablespace='0'  
order by a.relpages desc;omm-# omm-# omm-# omm-# 
                    relname                     | relkind | relpages | pg_size_pretty | reltablespace | relowner 
------------------------------------------------+---------+----------+----------------+---------------+----------
 pg_attribute                                   | r       |      184 | 1472 kB        |             0 |       10
 pg_proc                                        | r       |      140 | 1120 kB        |             0 |       10
 pg_depend                                      | r       |       59 | 472 kB         |             0 |       10
 pg_class                                       | r       |       52 | 416 kB         |             0 |       10
 pg_attribute_relid_attnam_index                | i       |       44 | 352 kB         |             0 |       10
 pg_proc_proname_all_args_nsp_index             | i       |       41 | 328 kB         |             0 |       10
 pg_proc_proname_args_nsp_new_index             | i       |       39 | 312 kB         |             0 |       10
 pg_proc_proname_args_nsp_index                 | i       |       39 | 312 kB         |             0 |       10
 pg_rewrite                                     | r       |       37 | 296 kB         |             0 |       10
 pg_depend_reference_index                      | i       |       34 | 272 kB         |             0 |       10
 pg_depend_depender_index                       | i       |       34 | 272 kB         |             0 |       10
 pg_description                                 | r       |       31 | 248 kB         |             0 |       10
 pg_attribute_relid_attnum_index                | i       |       30 | 240 kB         |