Oracle tablespace management

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One 、 Overview of table spaces

In order to facilitate the management and optimization of the database ,oracle The database is divided into logical areas of many table spaces , One oracle The database has one or more tablespaces , A tablespace corresponds to one or more physical database files . Tablespaces and data files are closely linked , interdependence , Create data files while creating table spaces , Empathy , When adding data files, you should also specify the table space . The database is physically determined by the size and number of data files , Logically, it is determined by the size and number of table spaces .
Table space is the basic method of data management , All user objects are placed in a tablespace , That is, users can create user objects only when they have the right to use the space , Otherwise, it is not allowed to create objects . While creating the tablespace , It is necessary to reasonably plan the storage settings of the table space , Allocate storage space of appropriate size .

1、 Table space properties

1、 type
2、 Management style
3、 Different matching methods
4、 Section management mode

2、 Type of tablespace

1、 Permanent table space
By default, both the system table space and the table space used by ordinary users are permanent table spaces .
2、 Temporary table space
Usually used to store sql Statement processing table and index information , Its space does not store actual data .
3、 Undo tablespace
This type is mainly used for transaction rollback , Provide read consistency . The database can have multiple drop table spaces at the same time , But only one undo tablespace can be activated at any time .
4、 Large file table space
Large file tablespaces are stored in a single data file , A single data file can be up to 128TB.

3、 The state of the table space

1、 Online status
Data can only be online , To access the data .
2、 Read write status
By default, all table spaces are read-write , Users with appropriate permissions can read and write the data of the table space .
3、 Read only status
The table space is read-only, which means that users can only read the data in the table space , You cannot modify the data of a tablespace .
4、 Offline
If a table space is set to offline state , It means that users cannot access the table space temporarily .

Two 、 The creation of a table space

In actual database tablespace management , According to the specific application , Create different types of table spaces , For example, the table space used for storing table data , Table space dedicated to storing indexes, etc .

1、 Table space creation syntax

create tablespace tablespace_name
datafile file_name datafile_options
storage_options

among ：tablespace_name Name the tablespace to be created ,file_name Is the name of the corresponding data file ,datafile_options Is the data file option ,Storage_options Is the storage structure option .

2、 Create a permanent table space , Set the initial size of the table space to 100MB, Automatically expand to 100MB, No maximum size limit , And the table space is online , Generate log

create tablespace tspace 1 datafile 'c:\oracle\tspace1.dbf' size 100m
autoextend on next 100m maxsize unlimited logging online permanent;

3、 ... and 、 Table space maintenance

1、 Set the default tablespace

Create a new user , If you do not specify a tablespace , The default permanent table space is system, The default temporary table space is temp, So if there are multiple users , Then all users should compete to use system and temp Table space , It will greatly affect oracle The efficiency of the system , The database administrator can modify the default permanent table space and temporary table space , The basic syntax is as follows .

alter database default [temporary] tablespace  New tablespace name 

Case study ： Put the temporary table space tspace4 Change to the default temporary table space

alter database default temporary tablespace tspace4;

Case study ： hold tspace3 Change to the default permanent table space .

alter database default tablespace tspace3;

2、 Rename a table space

Case study ： Set the table space tspace3 It is amended as follows tspace3_1

alter tablespace tspace3 renatspaceme to tspace3_1;

3、 Modify the state of the table space

modify tspace Is online

alter tablespace tspace online;

Set tablespace tspace Is offline

alter tablespace tspace offline;

Set tablespace tspace Is read-only

alter tablespace tspace read only;

Set tablespace tspace In read-write status .

alter tablespace tspace read write;

4、 Modify the size of the data file corresponding to the table space

The grammar is as follows

alter database datafile  Data files  resize  New file size 

Modify the table space tspace7 One of the corresponding data file sizes

alter database datafile 'c:\oracle\tspace7_1.dbf' resize 100MB;

5、 Increase the data space of the table

alter tablespace  Tablespace name  add datafile  Data files  size  file size ;

6、 Delete the data file of the tablespace

alter tablespace  Tablespace name  drop datafile  Data file name ;

7、 Modify the data file to auto extend

Set the table space tspace7 The data file of is set to automatic expansion

alter database datafile 'c:\oracle\tspace7_3.dbf' autoextend on next 10MB;

8、 Modify the name or location of the data file

alter tablespace  Tablespace name  rename datafile  Data file name  to  New data file name 

9、 Backup of table space

alter tablespace tspace 1 begin backup;

10、 Delete tablespace

drop tablespace tspace7;

Four 、 Table space query

Query the name of the tablespace 、 The management mode of the district 、 Information such as the management method of segments and table space types .

select tablespace_name,extent_management,allocation_type,contents from dba_tablespaces;

Check the name of the tablespace 、 File and space size

select tablespace_name,file_name,round(bytes/(1024*1024),0) total_space from dba_data_files;

5、 ... and 、 summary

The relevant contents here have not been sorted out yet , The article continues to be updated later , Recommended collection .

The commands involved in the article must be typed several times each like me , Only in the process of knocking can you find out whether you really master the command .

You can search by wechat 【 Xiaoqi JAVA interview 】 First time reading , reply 【 Information 】 Access to benefits , reply 【 project 】 Get the source code of the project , reply 【 The resume template 】 Get resume template , reply 【 Learning Roadmap 】 Get a learning roadmap .