Detailed explanation of Oracle database table space query method

Detailed explanation of Oracle database table space query method

When using Oracle database, it is very important to understand the database table space. Table space is a logical structure used to store table and index data in Oracle database. It is equivalent to the physical organizational unit of data storage in the database. When performing database management and performance optimization, it is often necessary to query and understand the usage of table spaces. This article will introduce in detail the method of querying table spaces in Oracle database and provide specific code examples.

1. Query the basic information of table spaces

1. View the names and types of all table spaces in the database

   SELECT tablespace_name, contents FROM dba_tablespaces;

Above The SQL statement will return the names and types of all table spaces in the database, including system table space (SYSTEM), temporary table space (TEMPORARY) and user table space (PERMANENT). Through this query, you can quickly understand the existing table spaces in the database. .

2. View table space data file information

   SELECT tablespace_name, file_name, bytes/1024/1024 AS size_mb FROM dba_data_files;

This SQL statement will return the name and size of each table space data file in the database (Unit: MB). Querying data file information can help us understand the storage structure of the database and the distribution of data files.

3. Check the usage of table space

   SELECT tablespace_name, (bytes - bytes_used) / 1024 / 1024 AS free_space_mb, bytes / 1024 / 1024 AS total_space_mb, (bytes - bytes_used) / bytes * 100 AS free_percent
   FROM dba_free_space;

Through the above SQL query, you can obtain the remaining space size and total space size of each table space and the proportion of remaining space.

2. Query the detailed information of the table space

1. View the table and index information in the table space

   SELECT tablespace_name, segment_type, COUNT(*) AS segment_count, SUM(bytes) / 1024 / 1024 AS total_size_mb
   FROM dba_segments
   GROUP BY tablespace_name, segment_type;

This paragraph The SQL query will return the number and total size of various types of segments (tables, indexes, etc.) in each table space, helping us understand the number and space occupied by different types of objects in the table space.

2. View the data files of the table space and the associated information of the table space

   SELECT tablespace_name, file_id, file_name, bytes/1024/1024 AS file_size_mb
   FROM dba_data_files;

This SQL query will return the data files of each table space And the name of the table space associated with it helps us better understand the relationship between data files and table spaces.

3. View the automatic expansion settings of the table space

   SELECT tablespace_name, file_name, increment_by/1024/1024 AS increment_size_mb, maxbytes/1024/1024 AS max_size_mb
   FROM dba_data_files;

This query will return the automatic expansion settings of each table space, including each automatic expansion The increment size and the maximum size limit of the table space help us rationally plan the use and management of the table space.

Through the above methods, we can fully understand the usage of table spaces in the Oracle database, so as to better manage the database and optimize performance. Hopefully these specific code examples will help readers better understand how to query and analyze tablespace information in Oracle Database.

The above is the detailed content of Detailed explanation of Oracle database table space query method. For more information, please follow other related articles on the PHP Chinese website!