Sorry, but I have not undersand this clearly. :-(
Could you please answer the single practical question (just "yes" or "no"):
if I perform

BEGIN;
INSERT INTO tbl(id, parent_id) VALUES(1, 2);    -- child first!
INSERT INTO tbl(id, parent_id) VALUES(2, null);  -- parent
COMMIT;

on master (assuming that parent_id foreign key is deferrable), DOES Slony
GUARANTEE that ANY subscriber will receive and SUCESSFULLY process this
data, or there is a probability that a subscriber will fail to update?


P.S.
Contrary to that, the query

BEGIN;
INSERT INTO tbl(id, parent_id) VALUES(2, null);  -- PARENT first
INSERT INTO tbl(id, parent_id) VALUES(1, 2);    -- child
COMMIT;

GUARANTEES that a subscriber will receive and process the data correctly,
it's obvious.


On 7/18/07, Andrew Sullivan <ajs at crankycanuck.ca> wrote:
>
> On Wed, Jul 18, 2007 at 08:11:40PM +0400, Dmitry Koterov wrote:
> > Will those two INSERT go ALWAYS in the same transaction on a subscriber
> or
> > not?
>
> No.
>
> > If not, nobody should use deferrable constraints together with Slony,
> > because sometimes query sequence correct for master will be incorrect
> for
> > slave.
>
> Also no.  Slony does things in "agreeable order", which is where much
> of the actual invention in Slony is (this was entirely Jan's idea,
> and it's a very clever one).  That is, it respects the visibility
> effects of MVCC _without_ having to replay the transactions in
> exactly the same order as they happened on the origin.  The
> explication of how this is to work is in the "concepts" doc that Jan
> originally wrote, which Chris already pointed you to.
>
> A
> --
> Andrew Sullivan  | ajs at crankycanuck.ca
> However important originality may be in some fields, restraint and
> adherence to procedure emerge as the more significant virtues in a
> great many others.   --Alain de Botton
> _______________________________________________
> Slony1-general mailing list
> Slony1-general at lists.slony.info
> http://lists.slony.info/mailman/listinfo/slony1-general
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.slony.info/pipermail/slony1-general/attachments/20070718/=
c42380d3/attachment.htm