Problems With Labels

This is in the context of (base) ClearCase, and more precisely of a new branching strategy.

1. Labels may overlap, so that the order of rules based on them is significant (this problem is not limited to labels, though)
2. Labels are heavy to apply (write operation on a single element version), their application is not atomic, their propagation over MultiSite asynchronous (there is no guarantee that you see all the labels that were applied on an other site—again, this is not an exclusive problem of labels).
3. Labels are confusing: they share a large flat namespace.
4. Types in ClearCase are second class citizen: the vob database is not indexed to make queries about them efficient.

• The radical solution to the first problem is to combine labels to use only one, and thus to resolve the contradictions.
• An approach to solve the second problem is to use incremental labels, applied only to as few versions as possible. To fight the propagation aspect, the only radical way is to apply the labels locally. This is all the more true if one considers global labels (across several vobs, typically created in an admin vob). Local labels won't fail you: they may end up selecting a sub-optimal version, but their interpretation wil not change silently.
• The third problem calls for conventions, for type names sharing a common prefix.
• I have no answer for now to the last problem (barring maintaining an external database...)

These 'solutions' seem contradictory. A resolution might call for support for incremental label families.

-- MarcGirod - 03 Oct 2007