No change to Firefox profile file size after vacuum run


Query regarding Vacuum of Firefox 11 profile.

I do not understand why Bleachbit Vacuum saves 8.2mb of disc space when Firefox is not running but on loading Firefox the file size reverts back to how it was before vacuum was run at 10.2mb.

Vacuum 8.2MB C:\Users\Username\Application Data\Mozilla\Firefox\Profiles\3jki4zf92.default\places.sqlite
Disk space recovered: 12.8MB

Everything is working fine and Firefox certainly loads quicker and is more responsive but I do not understand why the the total profile size is virtually the same as it was after vacuum was run.

Can you explain why the disc space recovered is not retained after re-loading Firefox?

I read on another forum that recent versions of Firefox are automatically vacuumed at idle time. I have no idea if this is true or not but it could explain why I am not finding any change in the file sizes after running Bleachbit.

Either I don't understand your post, or the math's off (not a big deal, though).
Don't know about Firefox vacuuming db's at idle time, but part could be what ALL is included in places.sqlite & how it's stored & displayed (when FF is running & you access bookmarks or history).

The idea behind vacuuming (I read) was to remove space left when entries were deleted. If that's true, if you del history totally -say at every shutdown, then it shouldn't result in much permanent size reduction.

There are certain files created at startup, like places.sqlite-shm & .sqlite-wal, that apparently hold temp data during a session, which (may) be written to places.sqlite at shutdown. Depending on what data is / is not written to the main file, could explain size changes.

If you del / securely erase the whole places.sqlite file, as many do, then a new file is created & (remaining) bookmarks are replaced next startup.

Truthfully, unless one has some GIANT profile db's, space recaptured by vacuuming probably isn't going to matter much - not on today's machines. I'm running a fairly fast machine w/ 8GB RAM, & I've never noticed much, if any diff in startup time or "responsiveness" of FF after vacuuming. But then I also clear all items on Clear Recent History every shutdown (EXCEPT site preferences, which is site cookie exceptions). Neither do I store cookies.

I am not sure how any version of Firefox actually does it, but here is how it probably works. If you ask Firefox to delete all your history at shut down, then it marks items deleted in the SQLite file. However, that doesn't necessarily shrink the file. Normally that is a good idea because vacuuming can take a lot of time, and if the file is needed, then vacuuming will make it unavailable which causes a delay.

If Firefox were smart, it might vacuuming at idle, shutdown, and when cleaning history.

Andrew, lead developer