Information Schema TABLES Table
Contents
The Information Schema table shows information about the various tables (until MariaDB 11.2.0, only non-TEMPORARY tables, except for tables from the Information Schema database) and views on the server.
It contains the following columns:
| Column | Description |
|---|---|
TABLE_CATALOG | Always def. |
TABLE_SCHEMA | Database name. |
TABLE_NAME | Table name. |
TABLE_TYPE | One of BASE TABLE for a regular table, VIEW for a view, SYSTEM VIEW for Information Schema tables, SYSTEM VERSIONED for system-versioned tables, SEQUENCE for sequences or, from MariaDB 11.2.0, TEMPORARY for local temporary tables. |
ENGINE | Storage Engine. |
VERSION | Version number from the table's .frm file |
ROW_FORMAT | Row format (see InnoDB, Aria and MyISAM row formats). |
TABLE_ROWS | Number of rows in the table. Some engines, such as XtraDB and InnoDB may store an estimate. |
AVG_ROW_LENGTH | Average row length in the table. |
DATA_LENGTH | For InnoDB/XtraDB, the index size, in pages, multiplied by the page size. For Aria and MyISAM, length of the data file, in bytes. For MEMORY, the approximate allocated memory. |
MAX_DATA_LENGTH | Maximum length of the data file, ie the total number of bytes that could be stored in the table. Not used in XtraDB and InnoDB. |
INDEX_LENGTH | Length of the index file. |
DATA_FREE | Bytes allocated but unused. For InnoDB tables in a shared tablespace, the free space of the shared tablespace with small safety margin. An estimate in the case of partitioned tables - see the PARTITIONS table. |
AUTO_INCREMENT | Next AUTO_INCREMENT value. |
CREATE_TIME | Time the table was created. Some engines just return the ctime information from the file system layer here, in that case the value is not necessarily the table creation time but rather the time the file system metadata for it had last changed. |
UPDATE_TIME | Time the table was last updated. On Windows, the timestamp is not updated on update, so MyISAM values will be inaccurate. In InnoDB, if shared tablespaces are used, will be NULL, while buffering can also delay the update, so the value will differ from the actual time of the last UPDATE, INSERT or DELETE. |
CHECK_TIME | Time the table was last checked. Not kept by all storage engines, in which case will be NULL. |
TABLE_COLLATION | Character set and collation. |
CHECKSUM | Live checksum value, if any. |
CREATE_OPTIONS | Extra CREATE TABLE options. |
TABLE_COMMENT | Table comment provided when MariaDB created the table. |
MAX_INDEX_LENGTH | Maximum index length (supported by MyISAM and Aria tables). Added in MariaDB 10.3.5. |
TEMPORARY | Until MariaDB 11.2.0, placeholder to signal that a table is a temporary table and always "N", except "Y" for generated information_schema tables and NULL for views. From MariaDB 11.2.0, will also be set to "Y" for local temporary tables. Added in MariaDB 10.3.5. |
Although the table is standard in the Information Schema, all but TABLE_CATALOG, TABLE_SCHEMA, TABLE_NAME, TABLE_TYPE, ENGINE and VERSION are MySQL and MariaDB extensions.
SHOW TABLES lists all tables in a database.
Examples
From MariaDB 10.3.5:
SELECT * FROM information_schema.tables WHERE table_schema='test'\G
*************************** 1. row ***************************
TABLE_CATALOG: def
TABLE_SCHEMA: test
TABLE_NAME: xx5
TABLE_TYPE: BASE TABLE
ENGINE: InnoDB
VERSION: 10
ROW_FORMAT: Dynamic
TABLE_ROWS: 0
AVG_ROW_LENGTH: 0
DATA_LENGTH: 16384
MAX_DATA_LENGTH: 0
INDEX_LENGTH: 0
DATA_FREE: 0
AUTO_INCREMENT: NULL
CREATE_TIME: 2020-11-18 15:57:10
UPDATE_TIME: NULL
CHECK_TIME: NULL
TABLE_COLLATION: latin1_swedish_ci
CHECKSUM: NULL
CREATE_OPTIONS:
TABLE_COMMENT:
MAX_INDEX_LENGTH: 0
TEMPORARY: N
*************************** 2. row ***************************
TABLE_CATALOG: def
TABLE_SCHEMA: test
TABLE_NAME: xx4
TABLE_TYPE: BASE TABLE
ENGINE: MyISAM
VERSION: 10
ROW_FORMAT: Fixed
TABLE_ROWS: 0
AVG_ROW_LENGTH: 0
DATA_LENGTH: 0
MAX_DATA_LENGTH: 1970324836974591
INDEX_LENGTH: 1024
DATA_FREE: 0
AUTO_INCREMENT: NULL
CREATE_TIME: 2020-11-18 15:56:57
UPDATE_TIME: 2020-11-18 15:56:57
CHECK_TIME: NULL
TABLE_COLLATION: latin1_swedish_ci
CHECKSUM: NULL
CREATE_OPTIONS:
TABLE_COMMENT:
MAX_INDEX_LENGTH: 17179868160
TEMPORARY: N
...
Example with temporary = 'y', from MariaDB 10.3.5:
SELECT * FROM information_schema.tables WHERE temporary='y'\G
*************************** 1. row ***************************
TABLE_CATALOG: def
TABLE_SCHEMA: information_schema
TABLE_NAME: INNODB_FT_DELETED
TABLE_TYPE: SYSTEM VIEW
ENGINE: MEMORY
VERSION: 11
ROW_FORMAT: Fixed
TABLE_ROWS: NULL
AVG_ROW_LENGTH: 9
DATA_LENGTH: 0
MAX_DATA_LENGTH: 9437184
INDEX_LENGTH: 0
DATA_FREE: 0
AUTO_INCREMENT: NULL
CREATE_TIME: 2020-11-17 21:54:02
UPDATE_TIME: NULL
CHECK_TIME: NULL
TABLE_COLLATION: utf8_general_ci
CHECKSUM: NULL
CREATE_OPTIONS: max_rows=1864135
TABLE_COMMENT:
MAX_INDEX_LENGTH: 0
TEMPORARY: Y
...
View Tables in Order of Size
Returns a list of all tables in the database, ordered by size:
SELECT table_schema as `DB`, table_name AS `Table`, ROUND(((data_length + index_length) / 1024 / 1024), 2) `Size (MB)` FROM information_schema.TABLES ORDER BY (data_length + index_length) DESC; +--------------------+---------------------------------------+-----------+ | DB | Table | Size (MB) | +--------------------+---------------------------------------+-----------+ | wordpress | wp_simple_history_contexts | 7.05 | | wordpress | wp_posts | 6.59 | | wordpress | wp_simple_history | 3.05 | | wordpress | wp_comments | 2.73 | | wordpress | wp_commentmeta | 2.47 | | wordpress | wp_simple_login_log | 2.03 | ...
From MariaDB 11.2.0
CREATE TEMPORARY TABLE foo.t1 (a int);
SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA='foo' AND TEMPORARY='y'\G
*************************** 1. row ***************************
TABLE_CATALOG: def
TABLE_SCHEMA: foo
TABLE_NAME: t1
TABLE_TYPE: TEMPORARY
...
TEMPORARY: Y
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