Is Perforce as good at merging as DVCSs?

Question

I've heard that Perforce is very good at merging, I'm guessing this has to do with that it tracks changes in the form of changelists where you can add differences across several files in a single blow. I think this implies Perforce gathers more metadata and therefore has more information to do smarter merging (at least smarter than Subversion, being Perforce centralized).

Since this is similar to how Mercurial and Git handle changes (I know DVCSs track content rather than files), I was wondering if somebody knew what were the subtle differences that makes Perforce better or worse than a DVCS like Mercurial or Git.

Answer 1

Very good, especially given perforce's competition (cvs, svn, etc) over most of its life, but no, not as good as Git. I can't speak to hg.

While some of this is off-base (the p4 shelf is now an old feature, no, you can't make a dvcs behave just like a vcs, and it seems silly to knock p4 for xcode dropping support) the choice bits about p4 merging headaches are accurate.

I don't think there's anything inherent to a distributed version control system that makes its merging naturally superior to a centralized system like perforce. Rather, the data models adopted by many dvcs's lend themselves to superior branch and merge tracking.

Perforce branch mappings? A cumbersome alternative to git's pointers and directed graph approach.

One key advantage of git over perforce -- tracking code through refactoring -- has nothing to do with git's status as a distributed version control, but rather the fact that it looks at both files and blobs of content as first class citizens in its data model. This is completely different from perforce, which keeps extensive metadata in its database on a file-by-file level: file state, history, attributes, changelists, while versioned file content is stored separately in a filesystem hierarchy.

Lastly, and this may be a bit unfair but I feel that if a version control system needs to have a file locking feature, it probably doesn't bode well for its branching and merging sophistication.

For a biased comparison of git vs. perforce (archived link). I also find it telling that perforce has itself jumped on the gitwagon.

Answer 2

It depends on how you use Perforce. I seen the 'everyone has a branch' approach and 'everyone uses the same branch' approach. I worked as a Release Engineer in a company that used to former approach and never had any issues.