On Mon, Aug 23, 2010 at 5:53 PM, Tarek Ziadé <ziade.ta...@gmail.com> wrote: > On Mon, Aug 23, 2010 at 5:48 PM, Michael Bayer <mike...@zzzcomputing.com> > wrote: >> >> >> Sent from my iPhone >> >> On Aug 23, 2010, at 8:29 PM, Tarek Ziadé <ziade.ta...@gmail.com> wrote: >> >>> Hello, >>> >>> I use the default options to run queries via sql expressions and I've >>> noticed that SQLAlchemy does a rollback >>> after every select using the mysql default engine. These rollback are >>> not really useful and eat 15% of the CPU time. >>> >>> Is this a normal behavior, part of the auto commit custom strategy >>> SQLAlchemy implements ? >>> >>> If yes, is there a way to avoid those extra rollbacks ? >> >> Because we're using a connection pool, putting the connection back into the >> pool without a rollback means you throw existing transactional locks and >> state into the pool as well, holding them open indefinitely and generally >> causing problems for subsequent usages of those pooled connections. >> >> However, we get a complaint about every 6 months from a mysql myisam user, >> who uses many ad-hoc connection checkouts (which in itself is a little >> unusual) and who would rather not have it (as myisam has no transactional >> integrity anyway). For those cases, we tell them to add >> rollback_on_return=False to their create_engine to turn the behavior off. >> >> But also maybe consider why you have a high volume of checkins, rather then >> working in some kind of transaction-per-logical-operation scheme (like a web >> request). > > > Thanks Michael !
Just for the record for others, the option is reset_on_return Cheers Tarek -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
