Synchronize database

[Mike Doty]

Anyone have a way to synchronize a database over the internet?
I'm currently applying a sequential transaction journal to remote
in-memory databases.

[Michael Mattias]

What do you mean, "synchronize?"

Do you mean make database "B" equal database "A"?

Or do you want to update both databases independently and somehow have it act as though updating one will update the other at the same time?

If you are using a journal technique, that sounds as good as anything else short of actually DOING the updates to both databases in real time. (Can you spell, "Client-Server? I think someone here actually offers some database products to do this. That sounds even better to me:ONE database!).

MCM

[Chris Holbrook]

May be a job for the differential backup - see post #35 http://www.powerbasic.com/support/pb...kup#post286504

[John Petty]

Mike
Depends whose data base you are using, some top end like MSSQL and I think Oracle have that built in as a background functionality.
Otherwise how to handle it is very dependant on the type of changes you are making and how many remotes could be making changes at the same time.
Michael is basically correct as a good client-server product should lose very little speed by using a slow connection. My own data base engine which is not client-server took a different aproach being designed from the ground up to run over slow connections ie 56k modem VPN connections. Both methods have different speed trade offs.
Both concepts fall down if the link is not available and the continuation of work is essential. Local copy with accurate UTC time stamped transactions can overcome most of the problems but there is no perfect solution. ie the network goes down and two remotes then sell the last single available item (airline seat or anything else you can think of), when the network comes up again one of the two remotes has sold a a non-existing item.
John

[Michael Mattias]

>and two remotes then sell the last single available item (airline seat ...

Bad Example.

I think the airlines will do that even when the network is UP.

[Chris Holbrook]

remote in-memory databases.

Sorry, I missed the "in-memory" bit. Forget the differential backup.

[Michael Mattias]

I did notice the "in memory" thing.

I ignored it. This application is screaming, "Client-Server! Client-Server!" or at the very least "One Database Accessed over the Internet! One Database Accessed over the Internet!"

[Michael Mattias]

Fifty-three cents says.... this application started out as something designed to do less.. like one less database.

Sometimes you just can't "upgrade" or "enhance" a program... you have to rewrite it to support the feature set now desired.

[John Petty]

My 2 cents, nobody that I know of has ever written or claimed to have written a perfect solution (except maybe airlines ). If this is important then the app has to be designed from the ground up with that goal in mind. Major applications budget for very expensive gauranteed up time networks, none of which will gaurantee 100% world wide so the programs have to alert those frail, unreliable things called humans to resolve issues of the type I decribed.