Why is rake db:migrate:reset not listed in rake -T?
Tasks that don't have a description will not show up.
EDIT: Looks like DHH removed the description from Rails 3 for a few tasks to 'cut down on noise'. rake db:setup has a note about db:reset though.
http://github.com/rails/rails/commit/983815632cc1d316c7c803a47be28f1abe6698fb
You can also use rake db -T -A to show all tasks, even uncommented ones. For reference these switches are doing the following:
-T, --tasks [PATTERN] Display the tasks (matching optional PATTERN) with descriptions, then exit.-A, --all Show all tasks, even uncommented ones (in combination with -T or -D)