On 3/16/16 7:59 AM, Stas Kelvich wrote: > On 12 Mar 2016, at 13:19, Michael Paquier <michael.paqu...@gmail.com> wrote: >> >> On Fri, Mar 11, 2016 at 9:35 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: >>> IMO this is not committable as-is, and I don't think that it's something >>> that will become committable during this 'fest. I think we'd be well >>> advised to boot it to the 2016-09 CF and focus our efforts on other stuff >>> that has a better chance of getting finished this month. >> >> Yeah, I would believe that a good first step would be to discuss >> deeply about that directly at PGCon for folks that will be there and >> interested in the subject. It seems like a good timing to brainstorm >> things F2F at the developer unconference for example, a couple of >> months before the 1st CF of 9.7. We may perhaps (or not) get to >> cleaner picture of what kind of things are wanted in this area. > > To give overview of xtm coupled with postgres_fdw from users perspective i’ve > packed patched postgres with docker > and provided test case when it is easy to spot violation of READ COMMITTED > isolation level without XTM. > > This test fills database with users across two shards connected by > postgres_fdw and inherits the same table. Then > starts to concurrently transfers money between users in different shards: > > begin; > update t set v = v - 1 where u=%d; -- this is user from t_fdw1, first shard > update t set v = v + 1 where u=%d; -- this is user from t_fdw2, second shard > commit; > > Also test simultaneously runs reader thread that counts all money in system: > > select sum(v) from t; > > So in transactional system we expect that sum should be always constant (zero > in our case, as we initialize user with zero balance). > But we can see that without tsdtm total amount of money fluctuates around > zero. > > https://github.com/kelvich/postgres_xtm_docker
This is an interesting example but I don't believe it does much to address the concerns that were raised in this thread. As far as I can see the consensus is that this patch should not be considered for the current CF so I have marked it "returned with feedback". If possible please follow Michael's advice and create a session at the PGCon unconference in May. I'm certain there will be a lot of interest. -- -David da...@pgmasters.net -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers