Does this patch enhance the "sync" loglevel, or do I need to enable something else? I currently have "loglevel config sync". Or do I need to put a special config switch in at build time?
Yes, the statements are debug_sync, for the provider.
Am I right in thinking that with "syncprov-checkpoint 10 5" I should see something happen at every checkpoint, in this case every 5 minutes?
(Dangerously talking off the top of my head without looking at the code...)
No, this happens when the slog is (or isn't) used, which happens during syncrepl client searches.
I've just deployed the patched 2.3.32 to the provider and one of the consumers, have been watching the logs for at least 15 minutes and haven't seen anything that looks like a CSN, at either end.
For those statements to hit, I believe it has to actually hit the slog, which isn't done in all cases. Let it run a bit longer...