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> I don't think it has anything to do with the fact that Git is distributed. I think it does since meta-data increases merge complexity, which is probably a he

by sdesol 5y ago

> I don't think it has anything to do with the fact that Git is distributed. I think it does since meta-data increases merge complexity, which is probably a headache when dealing with a distributed system. With a centralized system, you are basically creating a lock when you do a rename/copy/etc. which doesn't translate well to distributed systems. With Git as it is currently implemented, you only need to worry about one state which is the tree. With meta-data, the number of states that needs to be tracked can increase significantly. Having said all of that, I guess it probably wouldn't be too hard to implement a layer on top of Git that ensures every directory has something like a .git.meta file and have hooks that ensures all renames,copies,etc. are recorded in the meta-data file.

skissane 5y ago
> I think it does since meta-data increases merge complexity, which is probably a headache when dealing with a distributed system. I disagree. In Git, merging always happens locally, between two local commits; there is nothing distributed about merging itself. > With a centralized system, you are basically creating a lock when you do a rename/copy/etc. which doesn't translate well to distributed systems. I don't think that is really true. If I rename a file in Subversion, that doesn't involve "creating a lock". I rename the file locally (using "svn mv"), Subversion locally remembers I have done it, but doesn't send anything to the server. When I want to commit, it then contacts the server and uploads the commit data, including the rename tracking info. Now, that commit operation takes a write lock on the branch – to prevent any other commit for that branch being processed at the same time – but it is the exact same write lock regardless of whether renames are involved or not. If we take Subversion as an example of a centralised version control system with rename tracking, the rename tracking and the locking are orthogonal. (When I say "locking" here, I mean the internal locks within the Subversion server, not the end-user-visible advisory locks you get with the "svn lock" command–that advisory locking feature is unrelated to the topic of rename tracking.) Like Git, merging is essentially a local process in Subversion – the client constructs a merge commit, and then sends the completed merge commit to the server. The actual merge, meaning construction of the merge commit contents, always happens on the client side, at least as far as the core Subversion protocol is concerned.
- skissane 5y ago
  > Now, that commit operation takes a write lock on the branch – to prevent any other commit for that branch being processed at the same time In fact on the whole repo, since branches are just subdirectories. (Shows how long it has been since I've actually used Subversion, I'm starting to forget it.)

by sdesol 5y ago

skissane 5y ago

> I think it does since meta-data increases merge complexity, which is probably a headache when dealing with a distributed system. I disagree. In Git, merging always happens locally, between two local commits; there is nothing distributed about merging itself. > With a centralized system, you are basically creating a lock when you do a rename/copy/etc. which doesn't translate well to distributed systems. I don't think that is really true. If I rename a file in Subversion, that doesn't involve "creating a lock". I rename the file locally (using "svn mv"), Subversion locally remembers I have done it, but doesn't send anything to the server. When I want to commit, it then contacts the server and uploads the commit data, including the rename tracking info. Now, that commit operation takes a write lock on the branch – to prevent any other commit for that branch being processed at the same time – but it is the exact same write lock regardless of whether renames are involved or not. If we take Subversion as an example of a centralised version control system with rename tracking, the rename tracking and the locking are orthogonal. (When I say "locking" here, I mean the internal locks within the Subversion server, not the end-user-visible advisory locks you get with the "svn lock" command–that advisory locking feature is unrelated to the topic of rename tracking.) Like Git, merging is essentially a local process in Subversion – the client constructs a merge commit, and then sends the completed merge commit to the server. The actual merge, meaning construction of the merge commit contents, always happens on the client side, at least as far as the core Subversion protocol is concerned.

skissane 5y ago
> Now, that commit operation takes a write lock on the branch – to prevent any other commit for that branch being processed at the same time In fact on the whole repo, since branches are just subdirectories. (Shows how long it has been since I've actually used Subversion, I'm starting to forget it.)