Re: Implications of duplicate UUIDs on a server

On 2025-04-30 17:07, Doug Robinson wrote:
> On Wed, Apr 30, 2025 at 10:25 AM Doug Robinson 
> <[email protected]> wrote:
>
>     On Wed, Apr 30, 2025 at 4:17 AM Andreas Stieger
>     <[email protected]> wrote:
>
>         WANdisco is not a typical Subversion server implementation. For
>         synchronous multi-site replication (as opposed to svn sync
>         which is
>         asynchronous), it provides a proxy layer with a consensus
>         protocol
>         (think PAXOS, wsrep, raft).
>
>
> The WANdisco implementation is still asynchronous even though we try
> our hardest to make the replication occur absolutely as fast as possible.
> The PAXOS implementation is used to schedule the order of the repository
> updates.  The updates then occur in that order at every site as soon 
> as the
> data is available and the prior update has been applied.
>
> While a synchronous implementation might be great within a single data
> center, it comes with way too many problems for a world-wide WAN
> environment.


Certainly, I should have been more clear with that I mean: In a 
multi-master replication setup you need consensus at a point when you 
want a candidate transaction to become a revision. If there is only such 
candidate ready, you can commit to both your global sequence and to the 
committing the client rather quickly. Not every other node may see it 
instantaneously, but would not be able to commit to another until they 
are caught up. I briefly played with the wsrep replication API between 
svn_fs layers to make a FLOSS version of that but never got beyond a 
prototype.

Andreas