How to check table size in MySQL or MariaDB

Table-size checks in MySQL or MariaDB identify the tables driving storage growth before backups, replicas, schema changes, or retention jobs start taking longer than expected. A per-table report shows whether growth is concentrated in one busy table or spread across an entire application database.

Both servers expose table-size metadata through INFORMATION_SCHEMA.TABLES. The DATA_LENGTH and INDEX_LENGTH columns report allocated table-data and index bytes, while SHOW TABLE STATUS exposes the same core fields for a quick table-by-table cross-check inside the SQL client.

The sample outputs were verified with a disposable MariaDB 11.8 database. These figures are estimates rather than a filesystem audit. InnoDB row counts are approximate, DATA_FREE can describe tablespace-level free space rather than bytes one table can immediately reclaim, and MySQL can cache INFORMATION_SCHEMA table statistics until the session bypasses or refreshes them.

1. Open a MySQL or MariaDB client session on the target server.

   $ mariadb --user=dbadmin --password
   Enter password:
   Welcome to the MariaDB monitor.  Commands end with ; or \g.
   MariaDB [(none)]>

   Use mysql on MySQL systems. The SQL queries in the steps are the same on both servers.

2. Select the database that contains the table.

   MariaDB [(none)]> USE appdb;
   Database changed
   MariaDB [appdb]> SELECT DATABASE();
   +------------+
   | DATABASE() |
   +------------+
   | appdb      |
   +------------+

   Replace appdb with the database to inspect so the later queries can use DATABASE().

3. Show the size breakdown for one table from INFORMATION_SCHEMA.TABLES.

   MariaDB [appdb]> SELECT
       ->   table_schema AS `Database`,
       ->   table_name AS `Table`,
       ->   engine AS `Engine`,
       ->   table_rows AS `Rows (est.)`,
       ->   ROUND(COALESCE(data_length, 0) / 1024 / 1024, 2) AS `Data (MiB)`,
       ->   ROUND(COALESCE(index_length, 0) / 1024 / 1024, 2) AS `Index (MiB)`,
       ->   ROUND((COALESCE(data_length, 0) + COALESCE(index_length, 0)) / 1024 / 1024, 2) AS `Total (MiB)`,
       ->   ROUND(COALESCE(data_free, 0) / 1024 / 1024, 2) AS `Free (MiB)`
       -> FROM information_schema.TABLES
       -> WHERE table_schema = DATABASE()
       ->   AND table_name = 'orders'
       ->   AND table_type = 'BASE TABLE';
   +----------+--------+--------+-------------+------------+-------------+-------------+------------+
   | Database | Table  | Engine | Rows (est.) | Data (MiB) | Index (MiB) | Total (MiB) | Free (MiB) |
   +----------+--------+--------+-------------+------------+-------------+-------------+------------+
   | appdb    | orders | InnoDB |        4953 |       0.48 |        0.30 |        0.78 |       0.00 |
   +----------+--------+--------+-------------+------------+-------------+-------------+------------+
   1 row in set (0.00 sec)

   Replace orders with the table name to inspect. The TABLE_TYPE = 'BASE TABLE' filter keeps views out of the size report, and Rows (est.) is approximate for InnoDB.

4. Rank tables in the current database by total allocated size.

   MariaDB [appdb]> SELECT
       ->   table_name AS `Table`,
       ->   ROUND(COALESCE(data_length, 0) / 1024 / 1024, 2) AS `Data (MiB)`,
       ->   ROUND(COALESCE(index_length, 0) / 1024 / 1024, 2) AS `Index (MiB)`,
       ->   ROUND((COALESCE(data_length, 0) + COALESCE(index_length, 0)) / 1024 / 1024, 2) AS `Total (MiB)`
       -> FROM information_schema.TABLES
       -> WHERE table_schema = DATABASE()
       ->   AND table_type = 'BASE TABLE'
       -> ORDER BY (COALESCE(data_length, 0) + COALESCE(index_length, 0)) DESC;
   +-----------+------------+-------------+-------------+
   | Table     | Data (MiB) | Index (MiB) | Total (MiB) |
   +-----------+------------+-------------+-------------+
   | audit_log |       3.52 |        0.63 |        4.14 |
   | orders    |       0.48 |        0.30 |        0.78 |
   | customers |       0.17 |        0.11 |        0.28 |
   +-----------+------------+-------------+-------------+
   3 rows in set (0.00 sec)

   This ranking reflects allocated table and index space reported by the storage engine, not every file under the data directory.

5. Find the largest application tables across non-system databases.

   MariaDB [appdb]> SELECT
       ->   table_schema AS `Database`,
       ->   table_name AS `Table`,
       ->   ROUND((COALESCE(data_length, 0) + COALESCE(index_length, 0)) / 1024 / 1024, 2) AS `Total (MiB)`
       -> FROM information_schema.TABLES
       -> WHERE table_schema NOT IN ('mysql', 'information_schema', 'performance_schema', 'sys')
       ->   AND table_type = 'BASE TABLE'
       -> ORDER BY (COALESCE(data_length, 0) + COALESCE(index_length, 0)) DESC
       -> LIMIT 10;
   +----------+-----------+-------------+
   | Database | Table     | Total (MiB) |
   +----------+-----------+-------------+
   | appdb    | audit_log |        4.14 |
   | appdb    | orders    |        0.78 |
   | appdb    | customers |        0.28 |
   +----------+-----------+-------------+
   3 rows in set (0.00 sec)

   Use this server-wide query when the biggest application tables need to be found without mixing in system schemas.

6. Refresh table metadata before rerunning the size query when the values look stale.

   MariaDB [appdb]> ANALYZE TABLE orders;
   +--------------+---------+----------+----------+
   | Table        | Op      | Msg_type | Msg_text |
   +--------------+---------+----------+----------+
   | appdb.orders | analyze | status   | OK       |
   +--------------+---------+----------+----------+
   1 row in set (0.00 sec)

   ANALYZE TABLE can add I/O on large or busy tables. Run it during a low-traffic window when possible.

   On MySQL, run SET SESSION information_schema_stats_expiry = 0 before the size query when a one-off report must bypass cached INFORMATION_SCHEMA table statistics. MariaDB does not use that variable.

7. Cross-check the reported bytes with SHOW TABLE STATUS.

   MariaDB [appdb]> SHOW TABLE STATUS LIKE 'orders'\G
   *************************** 1. row ***************************
              Name: orders
            Engine: InnoDB
           Version: 10
        Row_format: Dynamic
              Rows: 4953
    Avg_row_length: 102
       Data_length: 507904
   Max_data_length: 0
      Index_length: 311296
         Data_free: 0
    Auto_increment: 8192
       Create_time: 2026-06-07 05:18:41
       Update_time: 2026-06-07 05:18:41
        Check_time: NULL
         Collation: utf8mb4_uca1400_ai_ci
          Checksum: NULL
    Create_options:
           Comment:
   Max_index_length: 0
         Temporary: N
   1 row in set (0.00 sec)

   SHOW TABLE STATUS exposes the same core size fields in bytes. MariaDB may show extra trailing columns, but Data_length, Index_length, and Data_free map to the same storage figures.

8. Exit the client session.

   MariaDB [appdb]> EXIT
   Bye