On Tue, Aug 2, 2016 at 10:33:15PM -0400, Bruce Momjian wrote: > I saw from the Uber article that they weren't going to per-row logical > replication but _statement_ replication, which is very hard to do > because typical SQL doesn't record what concurrent transactions > committed before a new statement's transaction snapshot is taken, and > doesn't record lock order for row updates blocked by concurrent activity > --- both of which affect the final result from the query. > > So, for statement replication, it is not a question of whether the code > has bugs, but that the replay is not 100% possible in all cases, unless > you switch to some statement-row-lock hybrid ability.
Oh, and one more problem with statement-level replication is that the overhead of statement replay is high, as high as it was on the master. That leaves minimal server resources left to handle read-only workloads on the slave. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Ancient Roman grave inscription + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
