Is it safe to delete unused matrix field tables from the DB? During design/dev I created a bunch of matrix fields that I have since decided not to use. I have deleted the fields, however, I notice that the matrix tables are still in the database. Is it safe to delete these manually, or is there some other cleanup that needs to happen as well (i.e. references within another table, etc.)?

Update: The problem is caused when changing the fieldtype from a matrix field to another field type, rather than deleting the field altogether, and creating a new one. Even if the field is subsequently deleted, the matrix tables will still remain, which results in orphaned data in the DB.
That shouldn't be the case... Those tables should have been deleted automatically when you deleted the fields.

Did you actually delete the fields themselves? Or did you simply remove them from your section's field layout? Make sure the actual fields were deleted within Settings > Fields



If you're positive those fields have been properly deleted...

Try updating to the latest version of Craft (v2.2.2587), which was released today. It includes this bug fix:


  Retroactively fixed a bug where some Matrix block rows would get left behind in the database when an element was deleted that had a Matrix field.


If that doesn't resolve the problem for you, I'd recommend submitting a bug report to Pixel &amp; Tonic. Submit the message via your Dashboard, so you can include a copy of your database and log files.