Dane Miller dane at greatschools.net
Wed Oct 31 22:52:01 PDT 2007
Hi Slony folks,

I've been reading docs trying to understand how Slony works.  I've tried to outline below my understanding of how an INSERT into the origin gets replicated to the subscriber.  Do I get the gist of it here?  If not, could someone be so kind as to correct me?  I hope this isn't too much of a newbie question, but I didn't find an answer in the admin guide on slony.info.

Tracing an insert from the origin to a subscriber (2 node cluster)

1. INSERT into the origin
2. AFTER ROW trigger executes logtrigger which inserts into sl_log_{1,2}
3. origin's slon checks sl_log_{1,2}, inserts event into sl_event, generates NOTIFY
4. subscriber receives NOTIFY, inserts event into its sl_event table, inserts confirmation into its local sl_confirm table.
5. subscriber inserts event into origin's sl_confirm table
6. subscriber queries origin's sl_log_{1,2} using event info
7. Subscriber applies result of #6 to its local tables.

whew!  If this has been covered elsewhere, please point me in the right direction.  I got this far by reading Slony-I-concept.pdf, but it seemed to cover more complex setups, and I got a bit lost in the detail.

Thanks,
Dane


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