> [snip] It is definitely not critical, but it makes 
> quite a difference in initial replication time for large databases 
> with foreign keys.

... it is actually quite critical for big data bases with foreign
keys... I have a data base which is ~50G on the slony replica (on the
server is more due to bloat), and if I leave the foreign keys on the
replica while doing the initial sync, it takes so much time to make the
sync that it can't then get in sync due to too much backlog. The size of
the backlog might not be so important if it wouldn't cause performance
degradation when it gets so big...

I have done all my replication only after I deleted the foreign keys on
the replica, and recreated them after the initial sync. Otherwise it
just won't work for me. I wonder how many sites have stumbled on this
small issue without knowing at all that it is an issue (it wont break
replication with a loud error, and a small test system will work for the
same schema), and decided that slony won't work for them...

So I would say it's critical...

Cheers,
Csaba.