On Jul 9, 2008, at 4:39 AM, William Pettersson wrote:
> The eeepc needs to query a serial device (RFID reader), check some
> stuff in the database and show some info. The thing is, the eeepc
> won't always have a network connection. Actually, it rarely will.
> So what I need to do is synchronise two databases, remote and local,
> and then just have my app query the local database.
This sounds like a human time scale task. That is, records will
accumulate only as fast as a single person can bring them in. Even if
it takes days between syncs, I can't imagine there will be all that
many records; hundreds, at most? Therefore, I don't see why you're
worried about sync time. Even the slow method of "read one from local
DB, write one to remote DB" should take a few seconds at most, even
over the Eee's wifi connection.
The mysqldump method won't be trivial. The first statement in a dump
file is a "DROP TABLE x IF EXISTS" followed by a "CREATE TABLE".
You'll have to strip that off for a sync operation.
Also, the mysqldump method probably breaks down completely if you ever
have two remote users, or equivalently, if the centralized DB is
allowed to change while the remote user is roaming about. You no
doubt have some unique ID columns, which your sync operation will have
to ensure remain unique in the merged DB. You need individual records
insertions wrapped in error-handling logic to make this robust.
History tells us that synchronization is hard. Whole companies have
crashed and burned by doing this badly. I wouldn't try to hack such a
project. It calls for a real language.
