--- In firebird-support@yahoogroups.com, Svein Erling Tysvær <svein.erling.tysvaer@...> wrote:

>
> Yes, you just add a record to a little log every time something changes, regardless of whether it is a delete, update or insert.

This is alternative:
In a simple case of one-way sync, table myChg on server should be: myChg(idChange, table, id, op).
For each table "MyTable" there is trigger.
CREATE TRIGGER MyTrigger FOR <MyTable> AFTER INSERT OR UPDATE OR DELETE AS
declare op varchar(1);
declare mID bigInt;
begin
op = 'U';
if (DELETING) then begin
op = 'D';
mID = old.id;
end
else begin
op = 'U';
mID = new.ID;
end
INSERT INTO MyChg(idChange, table, id, op )

> VALUES (GEN_ID(Chg_GEN, 1), <MyTable>, mID, op);

end
In the manner of ETL, for each table one need to filter out changes (idChange > idChg0) and forwarded to the client. In particular, separate op = "D" part of the table myChanges to. Suitable tool, fbExport, will give (with S switch) *.FBX file that after the transfer to the client, we can apply it with the same tools (I switch) to the table at the destination.
Export:
fbExport -S -D <database> -U user -P password -F <out file>.fbx -V TableName -Q "r where exists (select 1 from myChanges mc where mc.table = <tableName> and mc.idChange > idChg0 and r.id = mc.id)"
- zip all out files ...
- accept *.zip file, unzip and
Import (with option for Update or Insert !):
fbExport -I -D <database> -U -P -F <out file>.fbx -V TableName

In Delphi, I run fbExport.exe in batch with "cmd /C ..." for each table separately.
It is clear that (on the server) needs to be some AppServer for transfer. On the client, for accept, also. I use Midware components from Francois Piette but there are a wide range of tools for this purpose. Also, there are wide range of scenarios for mastering idChg0 and sync process. For example, the server periodically exports changes and leave the *. zip file to a familiar place where clients will find it.