gistfile1.txt

$results3 = client.query("SELECT table_schema AS 'Database name', SUM(data_length + index_length) / 1024 / 1024 AS 'Size (MB)' FROM information_schema.TABLES GROUP BY table_schema")
$results3.each do |row3|
puts "#{row3['Database name']} #{row3['Size (MB)']}"
end

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Output

information_schema 0.878906E-2
monitoring 0.174296875E3
notification 0.140625E0

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If I run it in mysql I get this

mysql> SELECT table_schema AS 'Database name', SUM(data_length + index_length) / 1024 / 1024 AS 'Size (MB)' FROM information_schema.TABLES GROUP BY table_schema;
+--------------------+--------------+
| Database name      | Size (MB)    |
+--------------------+--------------+
| information_schema |   0.00878906 |
| monitoring         | 174.29687500 |
| notification       |   0.14062500 |
+--------------------+--------------+

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