change tablespace oracle

In Oracle database, table space is a logical container used to store database objects. Common ones include tables, indexes, and LOB data types. When the table space has insufficient capacity or performance problems, the table space needs to be changed to ensure the normal operation of the database. This article will introduce how to change the table space in Oracle database.

1. Check the table space status

Before making table space changes, you need to check the status of the current table space. You can use the following statement to check the usage of table space:

select file_id, tablespace_name, bytes/1024/1024 as MB, maxbytes/1024/1024 as max_MB,
       round((bytes/maxbytes), 2) as usage_pct
from dba_data_files;

If the table space usage exceeds 80%, you need to consider changing the table space.

2. Increase the table space size

If the table space capacity is insufficient, you need to increase the table space size to meet the needs. You can use the following statement to increase the table space size:

ALTER TABLESPACE tablespace_name ADD DATAFILE 'filepath' SIZE size_in_MB;

For example, if you want to increase the capacity of 100 MB in the table space test, you can use the following statement:

ALTER TABLESPACE test ADD DATAFILE '/u01/app/oracle/oradata/mydb/test02.dbf' SIZE 100M;

Increase the table space size Afterwards, you need to recheck the table space usage.

3. Move table space

If the table space is stored in a different location on the disk, it will have an impact on database performance. To optimize database performance, tablespaces can be moved to faster storage devices. You can use the following statement to move the table space:

ALTER TABLESPACE tablespace_name MOVE DATAFILE 'filepath' TO 'new_filepath';

For example, if you want to store the table space test on the new disk /dev/sdb1, you can use the following statement:

ALTER TABLESPACE test MOVE DATAFILE '/u01/app/oracle/oradata/mydb/test02.dbf' TO '/dev/sdb1/test02.dbf';

Move the table space The following points need to be noted:

• Moving the table space will cause the read and write operations of the table space to slow down, so the operation should be performed during non-busy periods.
• Before moving the table space, you need to export the objects in the table space to other table spaces or databases, and then import the exported objects into the new table space.

4. Change the table space size

If the size of the table space exceeds actual needs, you can reduce the size of the table space to save disk space. You can use the following statement to reduce the table space:

ALTER DATABASE DATAFILE 'filepath' RESIZE size_in_MB;

For example, if you want to reduce the size of the data file/test02.dbf in the table space test to 50MB, you can use the following statement:

ALTER DATABASE DATAFILE '/u01/app/oracle/oradata/mydb/test02.dbf' RESIZE 50M;

It should be noted that before reducing the size of the table space, objects in the table space need to be moved to other table spaces, otherwise data loss may easily occur.

Summary

Table space is a very important concept in Oracle database. For operation and maintenance personnel, it is very important to master the method of changing table space. This article introduces the operations of adding, moving and shrinking table spaces. However, it should be noted that when performing table space changes, the integrity of the data and the performance of the database need to be taken into consideration. Reasonable planning of the use of table spaces is the key to database operation and maintenance. An important part of the work that cannot be ignored.

The above is the detailed content of change tablespace oracle. For more information, please follow other related articles on the PHP Chinese website!