Alguns comandos do MySQL

Medindo os tamanhos dos bancos:

SELECT
TABLE_NAME,
SUM(data_length + index_length) / 1024 / 1024 AS 'Data Base Size in MB',
SUM(data_free) / 1024 / 1024 AS 'Free Space in MB'
FROM
information_schema.TABLES
WHERE table_schema = 'nome_do_banco'
GROUP BY TABLE_NAME;

Medindo o tamanho das tabelas:

SELECT
table_schema,
table_name,
table_rows,
(data_length + index_length) / 1024 / 1024 AS 'Data Base Size in MB',
(data_free) / 1024 / 1024 AS 'Free Space in MB'
FROM
information_schema.TABLES
where table_schema = 'nome_do_banco'
ORDER BY data_length + index_length DESC