On Thu, Oct 7, 2010 at 2:08 PM, Aleksey Tsalolikhin
<atsaloli.tech at gmail.com> wrote:
> I see it doing about 890  inserts per second, and same again for
>   deletes.   that's 1780 SQL ops per second.
>
>   By comparison, updates (and slony does not use updates AFAIK so this is
>   my application's queries) run about 20 updates per second.
>

How many rows are affected per update?  Slony replicates each row
specifically, not the queries themselves.  So if you update 10000
rows, there will be 10000 records for slony to copy over to the other
end.

Naturally running slony replication will be slower because it uses a
log table to track changes, and fires off at least one trigger per row
insert/update/delete to track the changes.