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From:Warren Young Date:July 9 2008 2:48pm
Subject:Re: Duplicating tables - mysqldump or mysqlpp or?
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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.
Thread
Duplicating tables - mysqldump or mysqlpp or?William Pettersson9 Jul
  • Re: Duplicating tables - mysqldump or mysqlpp or?Warren Young9 Jul
  • Re: Duplicating tables - mysqldump or mysqlpp or?Jonathan Wakely9 Jul
  • RE: Duplicating tables - mysqldump or mysqlpp or?Paul Martin9 Jul
Re: Duplicating tables - mysqldump or mysqlpp or?William Pettersson9 Jul