I use the history in my browser often, to find sites I’ve visited. It’s precisely because I use it so often that it annoys me when it grows large. Especially as I moved my site around, I’m seeing lots of pages that no longer exist pop up in the history when I go to visit a site. I’d like to purge the old ones.
Tools -> Options -> Privacy has a setting, “Keep my history for at least __ days,” but note that “at least.” Mine’s gone way past the 7 days I have set.
By entering about:config, I discovered something: that’s called browser.history_expire_days_min, which I’d set to 7. But there’s also a browser.history_expire_days, still at 180. (Along with a browser.history_expire_days.mirror)
It turns out that the _min tells Firefox when it can delete an entry, but it won’t unless it’s short on space. Firefox 3 apparently makes this automatic, but wasn’t designed for people with a severe case of OCD who want things to age out after a while.
Setting history_expire_days (and history_expire_days.mirror) to 14 solved the problem: now things get saved for at least 7 days, but not to exceed 14. No more 6-month-old history entries!
Edit: A lot of people are searching for
history_expire_days.mirror, which is fairly cryptic. This portion of the source code was indexed by Google*, and defines
browser.history_expire_days.mirror as “a preference whose value mirrors that of browser.history_expire_days, to make the “days of history” checkbox easier to code.” So just set it to the same as history_expire_days if you’re changing it!
* It’s open source, so it’s not like it’s hard to find the source code.