Re: shared (database) file and multiple users
- Posted by Michael Sabal Jul 03, 2008
- 706 views
Yes I'm tryng using EDS database and I understand database locking/unlocking but main question is: how should I check, is there something changed. Every change in database can be detected if any user makes something, then little log file can be overwritten with date and time changes are done. But it means every user must all the time check the logfile to detect newer date and time from logfile. It means all the time some clientcomputers are connecting over LAN to chech logfile. Question is: is it possible to send some popup or mark to clientcomputer window that changes are available.
In MySQL, SQL Server, and the like, this would be done using triggers. EDS doesn't have triggers built-in, but if all your transactions are going through a server program, it should be pretty simple to implement. If all the clients are accessing the same file directly, then you should design your database in such a way that every write to a data table also writes to index table. The index table would look like...
key = {timestamp,primary_key,action} data = {}
The clients would have to poll the index to determine if new data is available.
A better design, IMO, would be to use a client/server model, where the clients never communicate with the database directly. They must communicate with the server, who can then prioritize the transactions, and send callbacks to the clients when there is new data.
