Rake task to get current database size

datasize.rake

# Run rake db:size to get a print of your database size in bytes.
# Works for Mysql, as for the others not really sure.


namespace :db do
  desc 'Print data size'
  task :size => :environment do
    
    database_name = ActiveRecord::Base.connection.instance_variable_get("@config")[:database]
    adapter = ActiveRecord::Base.connection.adapter_name.downcase
    sql = case adapter 
    when "mysql"
      "select SUM(data_length + index_length) as bytes from information_schema.TABLES where table_schema = '#{database_name}'"
    when "postgres"
      "SELECT pg_size_pretty(pg_database_size('#{database_name}'));"
    when "oracle", "oci"
      "select a.data_size+b.temp_size+c.redo_size+d.controlfile_size  from ( select sum(bytes) data_size from dba_data_files) a, ( select nvl(sum(bytes),0) temp_size from dba_temp_files ) b, ( select sum(bytes) redo_size from sys.v_$log ) c, ( select sum(BLOCK_SIZE*FILE_SIZE_BLKS) controlfile_size from v$controlfile) d;"
    else
      raise "#{adapter} is not supported"
    end
    puts ActiveRecord::Base.connection.execute(sql).fetch_hash.values.first
  end
end