Re: Logical decoding of sequence advances, part II

On Tue, Aug 23, 2016 at 7:10 AM, Kevin Grittner <kgrittn@gmail.com> wrote:
> On Mon, Aug 22, 2016 at 6:39 PM, Craig Ringer <craig@2ndquadrant.com> wrote:

>> Could you provide an example of a case where xacts replayed in
>> commit order will produce incorrect results?
>
> https://wiki.postgresql.org/wiki/SSI#Deposit_Report
>
> ... where T3 is on the replication target.

I should, perhaps, have mentioned that the cases where this is are
problem are "eventually consistent" -- it's a matter of being able
to see a state that violates business rule invariants or where data
which is "locked down" according to one part of the database is
still changing.  Such problems are prevented on a single database,
but would not be prevented on a logical replica where transactions
are applied in commit order.  Given enough time, the replica would
eventually settle into a state without the anomalies, similar to
some other products with eventual consistency.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company