Detailed Oracle table space (tablespace)

1 Overview

Draw the Oracle storage model in the form of an entity-relationship diagram, with the logical structure on the left and the physical structure on the right.

• There is a relationship drawn with a dotted line, which represents a many-to-many relationship between segments and data files. The dashed line is used to indicate the relationship because the relationship should not exist. A good relationship engineer should not allow many-to-many relationships.
• The table space entity eliminates the many-to-many relationship between the segment and the data file. A table space can contain multiple segments, and can be composed of multiple data files.

hint:

Creating tableand indexwhen we must bring属主（对应用户的表空间）

2 Grammar

2.1 Create

• Table space creator must have create tablespacesystem privileges
• When creating a table space, there are many default/optional clauses, as long as we know the most commonly used clauses.
• For a very complete one, please refer to: Oracle 12.2 Official Document-create tablespace

Common syntax: where [] means the parameter is optional

create [temporary | undo] tablespace "tbs"
datafile 'D:\oracle\tbs_01.dbf'
size 100m
[loggin | nologgin] -- 默认 loggin
[autoextend off] | [autoextend on next n1 maxsize m] -- 自动扩展, 默认 off, n1 默认 , m 默认 unlimited <= size n
[extent management local [uniform size n]] -- 默认 local, n = 64K;
[segment space management auto] -- 默认 auto, 且不建议被修改

-- 创建新用户，使用该表空间，方便测试
create user ODSDATA identified by 12345 default tablespace tbs
temporary tablespace temp quota unlimited on odstbs;
grant create session to ODSDATA;
grant resource to ODSDATA;

Syntax analysis:

1. create tablespace tbs 创建一个名为 "tbs" 的表空间(最常用)
	(1) temporary: 临时表空间,用于临时数据的存放
	(2) undo: 撤销表空间,用于重做日志文件的存放

2. datafile 'D:\oracle\tbs_01.dbf' size 5m 指定数据文件的位置和大小
	(1) 数据文件位置: "D:\oracle\tbs_01.dbf" -- 推荐使用绝对路径
	(2) 数据文件大小: 5m
	(3) 如果有多个文件,可以用逗号 , 隔开. 但是每个每个文件都要指明大小
		
3. loggin | nologgin 默认是 loggin,一般不写,但你要知道
	(1) loggin: 创建表空间时,同时生成重做日志文件(数据丢失时,可以恢复)
	(2) nologgin: 与 loggin 相反,但表创建速度快

4. autoextend 表空间是否自动扩展
	(1) off: 不自动扩展，默认值
	(2) autoextend on next 10m maxsize 100m
		自动扩展，增量是 10m，最大大小是 100m
		
5. extent management local | dictionary 区管理
	(1) local 本地管理,强烈推荐,从 Oracle 9i 开始，只能用 local，效率高
	(2) dictionary 数据字典管理,以前的管理方式。
		将数据文件中的每一个存储单元做为一条记录，在大量数据管理时，会产生大量的 insert、update 操作，严重影响性能。
		同时，长时间对表数据的操作，会产生很多磁盘碎片，这就是为什么要做磁盘整理的原因。

6. uniform size n: 指定 extent 的固定大小
    (1) size 8m: 固定为 8m
    (2) 若不填，extent 默认 64k (参考: dba_tablespaces 中的 initial_extent)

7. segment space management auto | manual
	(1) auto: 段空间由系统自动管理，只能使用在本地管理的表空间中(lob 字段的表除外)
	(2) manual: 段空间手动管理,目前已不用,主要是为了向后兼容

After we have created it, we can also query the parameters set above through the data dictionary:

SELECT ddf.file_id,
       ddf.file_name, -- 数据文件名称 datefile 'fileName'
       dt.tablespace_name, -- 表空间名称 tablespace tbs
       ddf.bytes / 1024 / 1024 || 'm' size_n, -- 初始数据文件大小,也就是 size n
       dt.logging, -- 日志属性 loggin
       ddf.autoextensible, -- 自动扩展
       dt.extent_management, -- extent management local | dictionary
       dt.allocation_type, -- system 长度自适应 | uniform 长度固定
       dt.segment_space_management, -- segment space management auto | manual
       dt.next_extent / 1024 / 1024 || 'm' next_n -- 数据文件增量大小,也就是 next n (当 allocata_type = 'uniform' 时，才有值)
  FROM dba_tablespaces dt, -- tablespace_name
       dba_data_files  ddf -- file_name, file_id, tablespace_name 
 WHERE ddf.tablespace_name = dt.tablespace_name
   AND dt.tablespace_name IN ('');

2.2 Modification

• The built-in table space of the system is not allowed to be modified, such as:system、sysaux、temp、undo、users
• The corresponding data file, location, and size have not changed after the table space name is modified
• A table space that is offline cannot modify its name

1. 调整数据文件的大小
alter database datafile 'D:\oracle\tbs01_1.dbf' resize 10m;

2. 调整数据文件为自动扩展
alter database datafile 'D:\oracle\tbs01_1.dbf' autoextend on next 20m maxsize 1g; -- 增量 20m, 最大长度 1g

3. 新增数据文件
alter database datafile 'D:\oracle\tbs02_1.dbf' size 2000m; -- 不自动扩展
alter database datafile 'D:\oracle\tbs02_1.dbf' autoextend on next 20m maxsize 1g; -- 自动扩展

2.3 Delete

• Any table space of the Oracle database can be deleted (except system、sysaux、temp、undo、users)
• Once the table space is deleted, it cannot be restored, so it is best to backup before deleting the table space
• You cannot delete a tablespace containing any active segments, you should make the tablespace offline before being deleted (very simple, do not go offline or close the running PL/SQL, deleting the tablespace will report an error)
• User to delete the table space must have drop tablespacepermission

1. 删除空的表空间（数据文件还在）
drop tablespace tbs;

2. 删除表空间 和 数据文件
drop tablespace tbs including contents and datafiles;

3. 仅从数据字典中删除表空间信息，但数据文件仍然存在，但已经失去作用
drop tablespace tbs including contents;

2.4 Query

Query table space information: (if there are multiple data files, group summation is required)

SELECT ddf.file_id 文件id,
       ddf.file_name 文件名,
       dt.tablespace_name 表空间名,
       dfs.block_id 块id,
       dt.contents 表空间类型,
       dt.extent_management 表空间管理模式,
       dt.segment_space_management 块空间管理模式,
       dt.allocation_type 分配类型, -- "system 系统随机" or "uniform 固定"
       dt.logging 日志模式,
       dt.force_logging 是否强制日志, -- 优先级 > 日志模式
       ddf.autoextensible 是否自动扩展,
       ddf.bytes / 1024 / 1024 "表空间初始大小(M)", -- 单位由 字节 -> MB
       ddf.maxbytes / 1024 / 1024 "表空间最大扩展到多少(M)", -- 0 表示自动扩展: off
       ddf.bytes / 1024 / 1024 "总大小(M)",
       dfs.bytes / 1024 / 1024 "剩余大小(M)",
       (1 - dfs.bytes / ddf.bytes) * 100 "使用率%"
  FROM dba_tablespaces dt, -- tablespace_name 
       dba_data_files  ddf, -- file_name, file_id, tablespace_name 
       dba_free_space  dfs -- tablespace_name, file_id, block_id 
 WHERE ddf.tablespace_name = dt.tablespace_name
   AND dfs.tablespace_name = ddf.tablespace_name
   AND dfs.file_id = ddf.file_id
   AND ddf.tablespace_name IN ('表空间名');

3 example

3.1 Create an automatic extension table space

Create a 100M database file student.dbf permanent table space tbs_student, automatically expand every 10M, the maximum is 500M

CREATE TABLESPACE tbs_student 
DATAFILE 'D:\table_space\student.dbf'
SIZE 100m
AUTOEXTEND ON NEXT 10M MAXSIZE 500M -- 自动扩展, 每次扩展 10M, 最大扩展到 500M
PERMANENT -- 永久表空间，默认
EXTENT MANAGEMENT LOCAL;

Query the table space through the data dictionary:

SELECT dt.tablespace_name 表空间名,
       dt.contents 表空间类型,
       dt.extent_management 表空间管理模式, -- "LOCAL 默认,本地" or "DICTIONARY 数据字典"
       dt.segment_space_management 段空间管理模式, -- "AUTO 默认,自动管理" or "MANUAL 手动管理"
       dt.logging 默认日志属性, -- "LOGGING 默认" OR "NOLOGGING"
       dt.allocation_type 分配类型, -- "SYSTEM 系统自动分配" or "UNIFORM 统一分配"
       dt.next_extent 默认增量, -- next, 当 allocation_type = UNIFORM 时，才有值
       ddf.file_id 文件id,
       ddf.file_name 文件名,
       ddf.autoextensible 是否自动扩展,
       ddf.bytes / 1024 / 1024 "表空间初始大小 M", --,单位
       ddf.maxbytes / 1024 / 1024 "表空间最大扩展到多少 M"
  FROM dba_tablespaces dt, -- tablespace_name
       dba_data_files  ddf -- file_id  
 WHERE ddf.tablespace_name = dt.tablespace_name
   AND ddf.tablespace_name = 'TBS_STUDENT';

search result:

3.2 The table cannot be expanded in the table space

the reason:

• The table space is full!
  • Table space automatic expansion is not set
  • Or set the table space automatic expansion, but exceeded MAXSIZE

Test user preparation

-- 表空间创建语句
CREATE TABLESPACE "TESTTBS_02" DATAFILE 
'D:\TABLE_SPACE\TESTTBS_02.DBF' SIZE 1m
AUTOEXTEND ON NEXT 1m MAXSIZE 2m
EXTENT MANAGEMENT LOCAL 
SEGMENT SPACE MANAGEMENT AUTO;

-- 测试用户
CREATE USER test_tablespace IDENTIFIED BY 12345 DEFAULT TABLESPACE TESTTBS_02;
GRANT CREATE SESSION TO test_tablespace; -- 允许登录
GRANT RESOURCE TO test_tablespace; -- 不对用户表空间进行限制

Test statement:

CREATE TABLE test_tablespace.stu_info (
  ID   NUMBER(10),
  NAME VARCHAR2(30)
);

DECLARE
   v_sql_insert VARCHAR2(500);
BEGIN
   -- 模拟插入语句
   v_sql_insert := 'INSERT INTO test_tablespace.stu_info (id, NAME) VALUES (:b1, :b2)';

   FOR i IN 1 .. 100000 LOOP
      EXECUTE IMMEDIATE v_sql_insert
         USING i, 'a' || i;
   END LOOP;
END;

Error screenshot:

4 extension

Reference sentence:

1. 修改表空间名
ALTER TABLESPACE old_name RENAME TO new_name;

2. 设置数据库的默认表空间
ALTER DATABASE DEFAULT TABLESPACE mytbs;

3. 设置数据库的默认临时表空间
ALTER DATABASE TEMPORARY TABLESPACE temptbs;

4. 查询数据库的默认表空间
SELECT t.username, t.default_tablespace, t.temporary_tablespace FROM dba_users t;

5. 允许数据文件自动扩展
ALTER DATABASE DATAFILE 'D:\oracle\tbs01_1.dbf' AUTOEXTEND ON NEXT 10m MAXSIZE 100m;

6. 使用表空间脱机/联机 （有效/无效）
ALTER TABLESPACE tbs01 ONLINE; -- 联机、有效
ALTER TABLESPACE tbs01 OFFLINE; -- 脱机、无效

7. 使表空间只读（仍可执行 drop 删除对象操作）
ALTER TABLESPACE tbs01 READ ONLY;

8. 使表空间可读写（脱机状态的表空间不能修改为读写状态）
ALTER TABLESPACE tbs01 READ WRITE;

4.1 Frequently Asked Questions

1. It is auto-expanding, why does it prompt that there is insufficient space?

• Exceeded maxsize, refer to the above example 3.1 Table cannot be expanded in the table space

AUTOEXTEND ON NEXT 1m MAXSIZE 2m

2. What is the default next value of autoextend on?

• When allocation_type = SYSTEMtime, next unified value assigned by the system, is not fixed
• When allocation_type = UNIFORMtime, next value is fixed, the following

extent management local uniform size 8m -- next = 8m

4.2 Related knowledge points

• Oracle table space, segment, area, block detailed