Dette link har en ret intens forespørgsel... som vil give dig mere, end du har brug for...:
SELECT s.schema_name,
CONCAT(IFNULL(ROUND((SUM(t.data_length)+SUM(t.index_length)) /1024/1024,2),0.00)) total_size_in_MB,
CONCAT(IFNULL(ROUND(((SUM(t.data_length)+SUM(t.index_length))-SUM(t.data_free))/1024/1024,2),0.00)) data_used_IN_MB,
CONCAT(IFNULL(ROUND(SUM(data_free)/1024/1024,2),0.00)) data_free_IN_MB,
IFNULL(ROUND((((SUM(t.data_length)+SUM(t.index_length))-SUM(t.data_free))/((SUM(t.data_length)+SUM(t.index_length)))*100),2),0) pct_used,
COUNT(table_name) total_tables
FROM INFORMATION_SCHEMA.SCHEMATA s
LEFT JOIN INFORMATION_SCHEMA.TABLES t ON s.schema_name = t.table_schema
WHERE s.schema_name = 'abc' -- give your schema name
GROUP BY s.schema_name
ORDER BY pct_used DESC;