Marco Canderle wrote:

>Hi, I'm new here so hello everyone. I've been experimenting with Slony-I to
>deploy a replication system for the database at my work.
>
>My objective is to have a master server in headquarter office, replicating
>to every slave server at the satellite offices. The idea is that users
>located in headquarters read from and write to master server. The users
>located in satellite offices read from the local slave server and write
>directly to the master server (which then replicates to all slaves
>databases, including the one who originate the write).
>This has to be done this way mainly for two reasons:
>   -If the master gets offline, the remote users can continue accessing
>information because they read from the local slave server.
>   -An increase in the response time: The system is web-based (implemented
>in PHP). For the remote users, in the other end of the country, the response
>time is much more slower than for the users near the master server, due to
>the Internet connection. And the majority of the database access are reads
>not writes.
>
>As I said, Reads are solved locally by every local slave server, and writes
>are routed directly to the master server, which then replicates the changes
>made.
>Here is where my problem arise. If a user is connected to a slave server and
>needs to make changes to de database, the writes will be passed to the
>master server. The master will make the corresponding changes and Slony-I
>will replicate this changes back to the slave who passed the writes (and all
>other slaves). All this steps adds a delay until the remote user can see the
>changes he/she made to the database reflected in his screen. For example if
>the user adds a new product to the database, he won't see it in the products
>list until  the replication takes place.
>This kind of situations can make the system show wrong information, which is
>dangerous in some scenarios of my system.
>
>So I ask: Are there any solutions that may help me reduce/avoid this delay
>  
>

use fiber channels between masters and slaves and robust high 
performance hardware?