cleaning out a Mercurial Repository

There are a bunch of file in the history of my hg repo that have been removed. They are causing the repo to get pretty big (several of them are images, and sql dumps fr开发者_如何学Com early in the project, among other things that never should have been comitted in the first place).

How do I get mercurial to forget about that stuff and get my repository down to a reasonable size again?

Should I just make a copy of the files (and the .hgignore) and make a new repo, while archiving the old one for future reference?

See:

$ hg convert --help

...

$ hg convert --filemap fmap old new

where file fmap contains something like:

exclude path/to/file/to/purge

(src: https://www.mercurial-scm.org/pipermail/mercurial/2008-August/020721.html)