Debian’s binary packages are only built when they are uploaded (or when a binNMU is requested, but that doesn’t happen frequently). They are never rebuilt later. This means that some binary packages in etch weren’t build in an up-to-date etch environment, but possibly in a much older environment.

Is this a problem? It depends. Old packages don’t benefit from the improvements introduced in Debian after they were built. Like new compiler optimizations, or other changes in the toolchain that could induce changes in binary packages.

For example, some files used to be at some place, but are now put at another place. Also, some parts of maintainers scripts are automatically generated, and would be different if the package was rebuilt today.

But is it really a problem? Are our packages _that_ old? Also, when a big change is made in the way we generate our binary packages (like Raphael Hertzog’s new dpkg-shlibdeps), when can we expect that the change will be effective in all packages?

I went through all binary packages in unstable (as on 24/06/2007) (both main, contrib and non-free packages) on i386. Using dpkg-deb –contents, I extracted the most recent date of each package (which can reasonably be taken as the date of the package’s creation). And here are the results.

Most packages are actually quite recent. 9008 packages (43%) were built after the release of etch. And 19857 packages (94%) were built after the release of sarge. But that still leaves us with 1265 packages that were built before sarge was released, and even one package (exim-doc-html) that was built before the release of woody! (the removal of this package has been requested, so we will soon be woody-clean :-)

Now, what could we do with this data? We could review the older packages, to determine if:

• They would benefit from a rebuild (by comparing them the result of a fresh build) <= I'm planning to work on that
• Integrate that data with other sources of data (popcon, for example), to see if the package should be removed. Such old packages are probably good candidates for removal.

Here is the full sorted list of packages.