Synchronisation in Microsoft Access

[jack1234]

Please consider the situation below:
There is a central server and there are many client PCs connected to the server. On each client PC, there is an access database file that will be frequently updated by the user of the PC.

What I want to do is to allow the user on each of the client PC to backup their database file to the central server;

At the server side, it is free to use any architecture(eg using file system or another database to store the file) to facilitate the backup purposes. One of simplest solution is to upload the entire database file to the central server everytime. However, the problem is the access database file on each client PC is quite big, hence it is better not to upload the entire file but only to upload the updated data to the central server.

Is there a way to synchronise the data with central server without upload the entire database file? What kind of architecture should built up in the central server if there is a way?

Any input is welcome

 

[Dudley]

Hi Jack,
Welcome to the forum. I'm going to chime in, even though I don't have extensive knowledge on this. It sounds like you might want to search the forum for info about the "Front end / Back end" db structure in which the data tables are stored in a single file on the server (the Back end) and are accessed by individual files on each user's pc (the front ends).
Good luck.

 

[jack1234]

Let me input some more details. Each of the database that used by each of the users is not relevant to each other. Each user has their own database file. Those users has used the database for quite awhile, and we should not change the schema of their database. To upload and download the data from the server is a new requirement. There should be some login mechanism for each of the users.

There is two button at the access form, which marked as "upload data" and "download data". The user communicates with the server via the internet. When they upload the data, the server side data will be overriden with the data they uploaded. When they download the file, their PC data will be overridden by the database data.

But since the user connect to the remote server via dial up modem, it is very slow to uploaded and downloaded their entire database file to and from the server, since their file size is about 50MB. But most of the capacity is occupied by the access form, not the data itself. It only has about 10 tables with not much data.

I am thinking of, to extract the data part of the mdb file, make it as a new mdb file with much more smaller file size, and upload to the server. Is it possible?

For the replication, I have considered about it. But it includes the changes to the user database they are using currently.

By the way, it needs to support about 20,000 users.

 

[dfenton]

Have you looked into roving profiles? The way that works is that your user profile is stored on your PC but synchronized with the server so that each computer you log onto synchronizes your profile folder with the server. This would give you automatic backup.

It sounds to me like the database ought to be stored on the servers in the first place -- all data should be stored on the server because that makes the workstations completely replaceable.

--
David W. Fenton
David Fenton Associates
http://dfenton.com/DFA/

 

[John_W]

You should still look a a Front End/Back End database architecture. That way you can split your application into 2 files - one containing the forms, querys etc and the other containing just the data tables. You would then want to restrict your upload/download to the Back End.

Impressed by your 20k users by the way!

 

[gemma-the-husky]

why do your users need to backup on your servers - if they have small single user dbs's why can't they back up on usb-datakeys or the like

is their data misison critical?