On Oct 2, 2012, at 5:01 PM, George Sakkis wrote: > On Oct 2, 10:39 pm, Michael Bayer <mike...@zzzcomputing.com> wrote: > >> On Oct 2, 2012, at 4:29 PM, George Sakkis wrote: >> >>> I had the impression that the Session’s unit of work figures out >>> automatically the potential object dependencies and makes sure that >>> the insertion order is consistent to a topological sort but apparently >>> I misunderstood. I postedhttps://gist.github.com/3822855as an >>> example. >> >>> In the first case (object_lists = [authors, books]), first a bunch of >>> Authors is committed and then a bunch of Books. As expected this >>> always succeeds. The next two cases though where authors and books are >>> commited at once may or may not succeed. Why it doesn't use the >>> topological sort of the tables and why it is not deterministic? >> >> on a quick glance I see no usage of relationship(). The topological sort is >> based on the relationship() paths built between mappers, not the foreign >> keys. > > Ah, I see. Out of curiosity, why it's not consistent across runs (i.e. > always fail)? > > Thanks for the super prompt reply!
if I had to guess it would be because the topological sort relies upon Python sets and therefore dictionary ordering, which is non-deterministic. -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@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.
