De S. Prakash, encontrado em Fórum MySQL :
SELECT table_schema "database name",
sum( data_length + index_length ) / 1024 / 1024 "database size in MB",
sum( data_free )/ 1024 / 1024 "free space in MB"
FROM information_schema.TABLES
GROUP BY table_schema;
Ou em uma única linha para copiar e colar mais facilmente:
SELECT table_schema "database name", sum( data_length + index_length ) / 1024 / 1024 "database size in MB", sum( data_free )/ 1024 / 1024 "free space in MB" FROM information_schema.TABLES GROUP BY table_schema;