On Tue, Oct 07, 2003 at 06:09:57PM +0100, Andy Baxter wrote: > - add an extra item to the package information which gives the version > number of the earliest previous version you can safely downgrade to by > running the installed package's remove script followed by the earlier > version's install script. This would probably allow most packages to > downgrade ok, but still give some way of stopping the system breaking > even worse when incompatible changes have been brought in. (e.g. when a > package has been split or renamed). I don't know the package management > system well enough to know if this would be the best way, but some > system like this where the information on how to safely downgrade is > put into the new package rather than the old one which nobody is going > to have the time to re-write, might work. This would require vast amounts of manpower. It's not going to happen. Debian does not support downgrades, and will not anytime soon. > - alternatively, cache all script-based changes (i.e. those which > involve more than just loading a file from a package) to the system > into some kind of diff archive whenever you upgrade. This is probably > not the best way as it would get unwieldy for a history longer than > maybe half a dozen changes, but it might work as a stop-gap measure to > allow some degree of downgrading where the user notices the problem > fairly quickly. This method would also have the problem that the > rollback could only go back along the previous path, whereas the > previous method would give a generalised safe method of downgrading > packages in whatever way the user wants. This is an approximation of the correct solution. The common name for it is a "backup" system (you've added delta compression, but that's not necessary). There are many packages providing backup solutions in Debian. I suggest you use one of them. -- .''`. ** Debian GNU/Linux ** | Andrew Suffield : :' : http://www.debian.org/ | `. `' | `- -><- |
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