title: Why does the MySQL file that contains my table's data not change size when I add data to the table?
body: <p>The files in which MySQL stores the table data don't seem to grow when I add data to the tables. They seem to start at 9k and stay there.</p>
  
  <p>The context of this question is that I wanted to create a database on my fastest drive (which is not the drive on which MySQL is installed). I worked out how to do this by setting the datadir variable and this seems to have worked: when I create a new database I see a folder named for the database in datadir, and when I create a table in that database then the folder gets a new file called table.frm. </p>
  
  <p>Is the .frm file not where MySQL stores the table's data? If 'no', then where is the data being stored? If 'yes' then why doesn't the file grow in size when I add millions of records to the table?</p>