== Shared Repository Extension ==

'''This extension is not distributed with Mercurial.'''

''Author: Brendan Cully''

Repository: http://hg.kublai.com/mercurial/extensions/sharedrepo

'''''Note:''''' As of 1.3, this extension will be made obsolete by the ShareExtension bundled with Mercurial.

=== Overview ===

This extension adds a `--shared` option to the clone command. When used, the
destination will simply use a pointer to the source's repository, instead
of copying it.  This can make clones faster and cheaper, especially if your filesystem doesn't support hardlinks. 

What is a typical usage scenario?

=== Caveats ===

Note that an operation performed in ''any'' shared repository will immediately affect ''all'' of its peers.  In effect, it is as though `commit` instantly and atomically pushes to the repository's parent ''and all of its siblings'' (i.e. any other shared clones of the same parent).  But, of course, there is no push: `commit` simply writes in the `.hg/store` directory shared by all peers.  

In particular, operations that destroy or modify history -- `strip`, `rebase`, etc. -- will also destroy or modify history in all of the shared clone's peers.  For example, if you accidentally strip too many revisions in a shared clone, poof! you've just stripped those revisions from all of its peers.  If you are experimenting with destructive operations, you should make a full clone and play around in it first.

Also, think carefully about the interaction between Mercurial Queues (MqExtension).  Because `.hg/patches` is ''not'' shared between repositories, it's possible for different shared repositories to have independent patch queues.  But MQ commands like `qpush` and `qpop` create and destroy history, so pushing/popping patches will affect all of the shared clone's peers.  It's probably not a good idea to mix MQ and shared clones; if you do so, you should definitely avoid pushing/popping patches in one clone while another clone has patches applied.

In short, this is a small modification that deeply affects Mercurial's usual "clones are independent" contract.  Make sure you understand what it does before you shoot yourself in the foot!

=== Configuration ===
Configure your .hgrc to enable the extension by adding following lines:

{{{
[extensions]
sharedrepo = /path/to/sharedrepo.py
}}}

=== See also ===
 * LocalbranchExtension - for sharing the working directory

----
CategoryExtensionsByOthers