Re: [Slony1-general] Slony and Network Delays

Thu, 05 Jan 2006 06:36:03 -0800

Rod Taylor wrote: 
On Thu, 2006-01-05 at 08:25 +0000, Aaron Randall wrote:
  
Hi,

I was wondering whether anybody had any information they could give me 
about how Slony is affected by network delays.
    

Badly and network outages don't help anything. I suggest you use the log
based method for inter-site replication instead of allowing direct
connections. Slony's standard mode  was not designed to work around
network limitations.
I'm wondering if the OP was asking about network latency ? (hence 'delay').
This can be a problem for replication mechanisms if the propagation of update
records between nodes is not pipelined. In that case there will be a stall with
1 x RTT duration between each update. With a typical WAN latency of 50ms or
so this will limit replication performance to only 10 updates per second.
I have no idea if slony suffers from this problem, but seeing the post made me
think of this issue, which I have seen in other replication products.

Network partition, or transient outages would present problems for
replication too, but I'm not sure if the OP was asking about that set of problems.


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