conocer_las_tablas_mas_grandes_en

Visualizar por orden las tablas más grandes de todas las bases de datos en un servidor MySQL

Mostrar ordenadamente las 10 tablas de mayor tamaño entre todas las bases de datos MySQL..

SELECT  CONCAT(table_schema, '.', table_name),
        CONCAT(ROUND(table_rows / 1000000, 2), 'M')                                    rows,
        CONCAT(ROUND(data_length / ( 1024 * 1024 * 1024 ), 2), 'G')                    DATA,
        CONCAT(ROUND(index_length / ( 1024 * 1024 * 1024 ), 2), 'G')                   idx,
        CONCAT(ROUND(( data_length + index_length ) / ( 1024 * 1024 * 1024 ), 2), 'G') total_size,     
        ROUND(index_length / data_length, 2)                                           idxfrac
FROM   information_schema.TABLES ORDER  BY data_length + index_length DESC LIMIT 10;

Si se quiere buscar en una sola base de datos se debe agregar: WHERE table_schema = “db_name”
Si se quiere cambiar el límite de 10 resultados eliminar: DESC LIMIT 10

Ejemplo de resultado pidiendo a MySQL las 10 tablas más grandes del servidor.

+--------------------------------------------+--------+-------+-------+------------+---------+
| CONCAT(table_schema, '.', table_name)      | rows   | DATA  | idx   | total_size | idxfrac |
+--------------------------------------------+--------+-------+-------+------------+---------+
| xxxxxxxxxx.addresses                       | 22.83M | 3.17G | 1.35G | 4.53G      |    0.43 |
| xxxxxxxxxx.orderItems                      | 7.88M  | 1.72G | 0.79G | 2.51G      |    0.46 |
| xxxxxxxxxx.orders                          | 4.06M  | 1.03G | 0.88G | 1.91G      |    0.86 |
| xxxxxxxxxx.orderItemsAddresses             | 23.10M | 0.99G | 0.87G | 1.85G      |    0.88 |
| xxxxxxxxxx.customers                       | 0.98M  | 0.08G | 0.05G | 0.12G      |    0.63 |
| xxxxxxxxxx.complaint                       | 0.35M  | 0.05G | 0.03G | 0.07G      |    0.64 |
| xxxxxxxxxx.complaintCauseComment           | 0.22M  | 0.03G | 0.02G | 0.05G      |    0.48 |
| xxxxxxxxxx.admin_link_inventory_attributes | 0.44M  | 0.02G | 0.02G | 0.04G      |    1.37 |
| xxxxxxxxxx.complaintCause                  | 0.24M  | 0.03G | 0.01G | 0.04G      |    0.47 |
| xxxxxxxxxx.complaintReasonComplaint        | 0.21M  | 0.01G | 0.01G | 0.02G      |    0.95 |
+--------------------------------------------+--------+-------+-------+------------+---------+

Fuente: http://www.percona.com/blog/2008/02/04/finding-out-largest-tables-on-mysql-server/