Subject Re: Replication engine
Author robertjmunro
> > At 12/19/2001 08:53 PM (Wednesday), robertjmunro wrote:
> > >Would there be much interest in an open source replication engine
> > >(probably GPL)?
> >
> > Yes!
> >
> > I'd also love to hear what your particular requirements are.

It is being done for a project that I am working on for the charity
Viva Network. ( They want to be able to give
copies of their database to everyone in their network that wants one.

The problem is, many members of the network are in remote locations
where internet access is very expensive or difficult to come by. We
want to allow people to sycronise at any time by saving to a file and
e-mailing it to us, or even posting it on a floppy. We won't often be
able to make a remote TCP/IP connection to their database (although
that would be an option for some people).

> I would get involved in that, in my last company we did both
> forms of replication i.e.
> 1) A record has changed, replicate the whole record (simple,
> easy to code, heavy on NW traffic)

> 2) A record has changed, lets store thenew values to a role
> forward log and replicate just the changed data. More
> complex to code, more tables required, a bugger with Blobs.

I'd like to move straight to number 2 for VivaNet, but we could
develop a number 1 style version if people are interested. I was
thinking about having a table for changes to every field up to varchar
(X) where X is configurable depending on the database requirements,
and another for longer CHAR and VARCHARs as well as BLOBs.

> We also produced a DB Comparer that would run periodically
> to ensure DB's didn't get out of sync.

That sounds handy. I was thinking about doing that with checksums
that are transferred with the replication data.

Is there any chance of it being released to us?

So far I have come up with a cool name - FiBRE, for FireBird
Replication Engine (or Free InterBase Replication Engine, but I don't
want to call it that until Borland stop being silly, and relaese the
trademarks and 6.5 sourcecode etc.) and started a sourceforge
Everyone interested is invited to join the open forum there.

I have written a document describing some of the basic ideas, but I
haven't had a chance to upload it to the web site yet.

Robert Munro