afaik oracle does elaborate concurrency checking, as in it stores a log of what you can see on a cursor, and when you issue a transaction and a piece of what you want to update has been updated since you fetched that information, it raises an exception on commit.
Quoting Michael Bayer <[EMAIL PROTECTED]>: > > On Mar 28, 2006, at 10:41 PM, Daniel Miller wrote: > > > Michael Bayer wrote: > >> Optimistic concurrency checking simply means when you UPDATE or > >> DELETE rows, you insure that the returned row count matches > >> correctly. This is how Hibernate does it, and its how SQLAlchemy > >> does it. > > > > I don't think you've got that quite right. Checking the affected > > row count alone does not guard against most concurrency violations. > > In fact, the only assurance you get from that is that rows being > > updated/deleted have not previously been deleted. It does not > > detect if the data that's being modified has been modified by > > another process or session. > > > > Ok, its the most minimal level of concurrency checking. and yes, > thats all there is. I forgot about the version number thing, which > I had indended to add as optional behavior, ie. method #2. method #1 > and #3 are both too byzantine for my tastes. i should go add a > ticket for version numbering. > > > > ------------------------------------------------------- > This SF.Net email is sponsored by xPML, a groundbreaking scripting language > that extends applications into web and mobile media. Attend the live webcast > and join the prime developer group breaking into this new coding territory! > http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642 > _______________________________________________ > Sqlalchemy-users mailing list > Sqlalchemy-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/sqlalchemy-users > > ------------------------------------------------------- This SF.Net email is sponsored by xPML, a groundbreaking scripting language that extends applications into web and mobile media. Attend the live webcast and join the prime developer group breaking into this new coding territory! http://sel.as-us.falkag.net/sel?cmd=lnk&kid=110944&bid=241720&dat=121642 _______________________________________________ Sqlalchemy-users mailing list Sqlalchemy-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sqlalchemy-users
