Every six months the internet lights up with stories that Canonical & Co has done the unthinkable they have increased the number following the word Ubuntu. In other words they have release a new version. This is a well understood concept to differentiate releases of software. As the version increases it is expected that new features are introduced and old bugs are removed (hopefully more are removed than added).

Versioning distributions and releasing the versions separately is a common practice, employed by most if not all distributions out there. Ubuntu has adopted the policy of releasing regularly and quite often. But there is a different approach it revolves around a concept I call "Versionless" where you do not have a hard release but instead let the changes trickle down. In the application world these releases are often called nightly builds. With distributions it is a little bit different.

First of all its worth noting that distributions are not like applications. Distributions are collection made up by applications and a kernel, the applications that are included are usually stable releases and so the biggest unpredictability comes from the combination and configuration there of. As a result one of the important roles for distro developers is to ensure that the combination of the many applications does not lead to adverse side effects. This is done in several ways, the general method is to mix all the applications in a pot, the so called pre-release and then test the combination. The testing is done by whole community, as users often install these pre-releases to see if they see any quirks through their regular use. When the pre-release becomes stable enough it is pushed out the door as a public release.

In an ideal world after this whole process all the major bugs and issues would have been resolved and users go on to re-install/update their distribution installations to the new release -- without any issues. The problem is that even if the tests passed with flying colors does not mean that on the user will not experience problems. The more complicated a configuration that a user has the more chances they will notice bugs as part of upgrade. This is particularly evident where there are multiple interacting systems. Doing a full upgrade of a distribution it is not always obvious what change in the update has caused this problem.

Versionless distributions are nothing new, they has been a staple of Debian for a while. In fact it is the process for testing package compatibility between release, but it is also a lot more. There are two Debian releases that follow this paradigm, Debian Testing and Debian Unstable. As applications are packaged they are added to Debian Unstable and after they fulfill certain criteria, IE they have spent some time in Unstable and have not had any critical bugs filed against them, they are then passed along to Debian Testing. Users are able to balance their needs between new features and stability by selecting the corresponding repository. As soon as the packages are added to the repositories the become immediately available to user for install/upgrade.

What it really comes down to is testing outside your environment is useful but it cannot be relied solely upon. And when upgrades are performed it is important to know what has changed and how to undo it. Keeping track of changes for 1000's of updates is nearly impossible. So update small and update often, use Debian. Good packages managers are your best friend, but only second to great package developers!