oracle change tablespace

Oracle database is an efficient and reliable relational database management system, in which table space is a very important concept in Oracle database. Table space is part of the physical storage structure. It is a logical storage unit composed of data files that can be used to store or maintain tables, indexes, stored procedures and other database objects. Therefore, changing tablespaces in Oracle database is a very common operation. This article will introduce the methods and precautions for changing table spaces in Oracle database to help readers better master Oracle database management skills.

1. Methods of changing the table space

There are many ways to change the table space, which are introduced below:

1. Use the ALTER TABLE command

The method of using the ALTER TABLE command to change the table space is very simple. Just use the following command:

ALTER TABLE table_name MOVE TABLESPACE new_tablespace;

Among them, table_name refers to the table name of the table space to be changed; new_tablespace refers to the new table space name.

2. Use the data pump tool

The data pump tool is a very powerful data import/export tool that comes with Oracle database. It can export the data in the database to a file. Data from a file can also be imported into the database. By using the data pump tool, we can easily export the data of a certain table completely to a data file, and then import it into a new table space. The following are the steps to use the data pump tool to change the table space:

1) Export the table data to be changed in the table space to a file

Execute the following command in the command line:

expdp system/password tables=table_name directory=dir_name dumpfile=dump_file.dmp

Among them, system/password refers to the login user name and password of the Oracle database, table_name refers to the name of the table to be exported, dir_name refers to the directory of the data file to be exported, and dump_file.dmp refers to the name of the data file to be exported.

2) Create a new table space

Create a new table space in the Oracle database, the command is as follows:

CREATE TABLESPACE new_tablespace
DATAFILE 'path/to/new_tablespace.dbf'
SIZE 100M
AUTOEXTEND ON;

Among them, new_tablespace is the name of the new table space, path /to/new_tablespace.dbf is the path and name of the new table space file. SIZE 100M indicates that the initial size of the new table space is 100 MB. AUTOEXTEND ON indicates that the space will be automatically increased when the table space is insufficient.

3) Import table data into the new table space

Execute the following command in the command line:

impdp system/password tables=table_name directory=dir_name dumpfile=dump_file.dmp remap_tablespace=old_tablespace:new_tablespace

Where, system/password is the login username and password of the Oracle database , table_name is the table name, dir_name is the data file path specified when exporting data, dump_file.dmp is the name of the exported data file, old_tablespace is the original table space name, and new_tablespace is the new table space name.

2. Precautions for changing the table space

When changing the table space, you need to pay attention to the following matters:

1. Check the target table space

Before changing the table space, you need to check whether the target table space has enough space to accommodate the table to be moved. If the target table space does not have enough space, the move may fail or the table data may be incomplete after the move.

2. Moving large tables

For large tables, additional processing may be required when moving. If a problem occurs while moving the table, you may need to rerun the move command. Before rerunning the command, you need to cancel the move command and rerun it.

3. Back up the original table space

Before moving the table, it is best to back up the entire table space. If something goes wrong while moving the table and data is lost, backup can make it easier to restore the data.

4. Restrict user access to the table

In the process of moving the table, it is best to set the table to read-only status. This can prevent users from inserting, updating, or deleting operations on the table during the process of moving the table, causing data errors.

5. When using the data pump tool, you need to pay attention to the following matters

(1) Data pump export/import speed is very slow, so you need to give enough time when exporting/importing.

(2) When importing data, you need to use exactly the same command as when exporting, including parameters and options.

(3) Use the remap_tablespace option to specify the new tablespace to import data.

(4) When exporting data files, it is best to use the same version of the data pump tool as the target Oracle database, otherwise the data may be damaged or cannot be imported.

In short, table space is a very important concept in Oracle database, and changing table space is a very common operation in Oracle database management. Mastering the methods and precautions for changing table spaces can better ensure the security and stability of the database.

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