Hi,

We are using Slony on a production environment and are very pleased by it.

Our cluster is made of 1 master, 4 slaves that needs to be replicated 
fast, and 2 slaves for which the replication speed isn't a problem.

Here's our issue: In the sl_status view I notice that the st_lag_time is 
always between 1 and many seconds: it goes up to 10 seconds regularly, 
and approximatively one time a day, there is always a slave reaching 1 
min, for example while vacuuming.

I tried playing with the folllowing options:
     -s <milliseconds>     SYNC check interval (default 10000)
     -t <milliseconds>     SYNC interval timeout (default 60000)
     -o <milliseconds>     desired subscriber SYNC processing time
     -g <num>              maximum SYNC group size (default 6)

Now on the master I have:
-s 1000 -g 50
On the fast slaves I have:
-s 1000
And on the slow slaves:
-s 10000 -g 10

I tried lowering the SYNC check interval to 500ms with no real effect, 
and the master is already loaded enough anyway ;)

Is there an effective way to shorten the replication lag time ?

A Slony noob.

-- 
Laurent Raufaste
JFG Networks
<http://www.over-blog.com/>