Re: Streaming a base backup from master

On Fri, Sep 03, 2010 at 09:56:12AM -0400, Stephen Frost wrote:
> * Robert Haas (robertmhaas(at)gmail(dot)com) wrote:
> > The rsync code itself is not modular, I believe. I think the author
> > thereof kind of took the approach of placing efficiency before all.
>
> Yeah, I looked into this when discussing this same concept at PGCon with
> folks. There doesn't appear to be a good librsync and, even if there
> was, there's a heck of alot of complexity there that we *don't* need.
> rsync is a great tool, don't get me wrong, but let's not try to go over
> our heads here.

rsync is not rocket science. All you need is for the receiving end to
send a checksum for each block it has. The server side does the same
checksum and for each block sends back "same" or "new data".

The client and the server don't need to synchronise at all. If the
client sends nothing, the server sends everything.

The tricky part of rsync (finding block that have moved) is not needed
here.

Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> Patriotism is when love of your own people comes first; nationalism,
> when hate for people other than your own comes first.
> - Charles de Gaulle