Detailed explanation of the method of querying table space size in Oracle database

Oracle database is a commonly used relational database management system, and table space is an important part of the database to store data. It is very important for database administrators and developers to understand how to query the size of table spaces. This article will introduce in detail the method of querying the table space size in the Oracle database and provide specific code examples.

1. Use the system view to query the size of the table space
In the Oracle database, you can query the size information of the table space through the system view. Commonly used system views include DBA_TABLESPACES and DBA_DATA_FILES. The following is a specific code example to query the size of the table space through these two system views:

1. Query the size of all table spaces:

   SELECT tablespace_name, SUM(bytes)/1024/1024 AS "Size(MB)" 
   FROM dba_data_files 
   GROUP BY tablespace_name;

2. Query Specify the size of the table space:

   SELECT tablespace_name, SUM(bytes)/1024/1024 AS "Size(MB)" 
   FROM dba_data_files 
   WHERE tablespace_name = 'YOUR_TABLESPACE_NAME' 
   GROUP BY tablespace_name;

In the above code example, the file size information of the table space can be obtained by querying the dba_data_files system view, and the total size of each table space can be calculated through the SUM function. Size (in MB).

2. Use the control file to query the table space size
The control file is one of the key files of the Oracle database, which contains the metadata information of the database. The size information of the table space can be obtained by querying the control file. The following is a code example for querying the size of a table space:

SELECT tablespace_name, SUM(bytes)/1024/1024 AS "Size(MB)" 
FROM v$datafile 
GROUP BY tablespace_name;

In the above code example, the size information of the table space can also be obtained through the v$datafile dynamic performance view, and the total size of each table space can be calculated. .

3. Use USER_SEGMENTS to query table space usage
In addition to querying the size of the table space, you can also query the space used by each table space through the USER_SEGMENTS data dictionary view. The following is a code example for querying table space usage:

SELECT tablespace_name, segment_type, SUM(bytes)/1024/1024 AS "Size(MB)" 
FROM user_segments 
GROUP BY tablespace_name, segment_type;

In the above code example, the used space of different types of segments (such as tables and indexes) of each table space can be obtained by querying the user_segments data dictionary view. Condition.

Summary:
This article introduces the method of querying the size of table space in Oracle database, including using system views, control files and data dictionary views. At the same time, specific code examples are provided so that readers can choose the appropriate method to query the table space size according to the actual situation, helping administrators and developers better manage the database.

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