Re: Database Replication over Slow Link ???

fang_at_cs.wvu.edu (Tao Fang) wrote:
>We are trying to develop a distributed system over a slow network.
 ..
>should allow a user to query and UPDATE data from the database at any
>site.

 ..
>the same data at different site at the same time. If we use lock
>mechanism, what would happen if the link is down after the data is
>locked by a remote user? What will the performance be? Is there any

I've done this, and what I would ask is do you need to lock the data? A carefully designed application may not need to lock the data especially across sites. It may be there is an implicit lock in the application, e.g. Site 1 needs only to change Site 1's records, but needs to see Site 2/3. Or record 1 is controlled by site1 and site 2 alternately, in which case record the ownership as a field and only allow your application to write if you've got control.

Locks are pretty much unsustainable across WAN sites.

Rajiv Dhir
Rajiv_Dhir_at_lehman.com
The opinions I express are definitely my own. Received on Fri Jan 27 1995 - 12:50:08 CET