Delta

  • Thread starter Thread starter Murray Foxcroft
  • Start date Start date
M

Murray Foxcroft

Hi there,

I have a file on a server (XML doc) and the exact matching file on a PPC2003
device.
The file on the server changes.

The next time I connect with the device, I want to get the updated file.

This is over GPRS so I would only like to get the DELTA of the two files and
move that across.

Anyone done this before?

Thanks in advance.
 
Murray,

You'd have to write logic on the desktop that knows what the (continually
updated) delta would be and send that. Would you have multiple devices each
with multiple versions of the file, or will you be syncing with only a
single device? If SQLServer and SQLCe are options for you, merge/replication
does just that for you.
 
Hey, thanks for the reply.

Each user has a device - each user has an independant XML file of his items.
We do have CE replication available to us - but the app will run over GPRS -
costy - what is the replication overhead vs a simple delta solution?

Thanks in advance

Regards
 
Murray,

Once the initial snapshot of the database is downloaded, future replications
should only download the changes. You'll need to test with your own hardware
to see what the timing will be over GPRS, but I doubt you'll be able to
improve over it with a solution you write yourself, especially since XML
files are bulky compared to the compression that is part of SqlCe
replication.
 
We've got the compression part licked on the PPC so the files are GZip'd
before transport, when u say that future replications only download the
changes - if column X of row Y changes - then what is sent over the wire?

The whole row?
Just the chasnged column?

How does SQL CE manage this replication (looking in terms of system overhead
on the wire)
 
Murray,

I don't know the answer to your question about exactly what gets sent with a
single column change. You may want to ask on the SqlServerCe newsgroup.
 
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