For those of you pushing your MySQL instances to higher levels, you'll have realized at some point that all InnoDB tables share their indexing space into a single file (ibdata1, usually).
This has several very bad outcomes:
- the ibdata1 file becomes huge after some time (we've seen it pass the 8GB bar)
- starting the MySQL server takes longer
- deleting an InnoDB table *doesn't* reduce the space used by ibdata1
- you have to shutdown your server, remove ibdata1 completely, then restart the server in order to reinitialize the ibdata1 file to a 0-size file (but this is, of course, difficult or dangerous to do in a high-availability context)