Re: [sqlalchemy] Re: Strange ObjectDeletedError
sure, you commit too often, and if you're expiring too, then you're re-selecting all the time. On Feb 9, 2011, at 3:54 AM, Romy Maxwell wrote: > I never did understand the pros or cons of running autocommit=True, > aside from this flushing issue. Are there performance implications ? > > On Mon, Feb 7, 2011 at 1:22 PM, Michael Bayer > wrote: >> I actually just did a little bit of reverse course on this in 0.7. I've >> moved all the accounting into the try/except block so that the flush >> completes fully before the autocommit expires everything. This is a change >> to a pattern that's been the same way since 0.4 so hoping nothing bad >> happens when we put 0.7 out into betas. >> >> >> On Feb 7, 2011, at 2:52 PM, Romy Maxwell wrote: >> >>> Are there any downsides to setting expire_on_commit=False when using >>> autocommit=True ? In other words, should I expect to see stale data or >>> other side effects ? >>> >>> On Mon, Feb 7, 2011 at 8:30 AM, Michael Bayer >>> wrote: On Feb 7, 2011, at 7:42 AM, Romy Maxwell wrote: > Hey Michael, > > I didn't wanna revive a really old thread > [http://www.mail-archive.com/sqlalchemy@googlegroups.com/msg16598.html], > so I figured maybe you won't mind the email. > > I don't understand why, in the thread, using autocommit=True makes the > object unreachable, or what that actually means. I'm assuming it was > referring to the latter part of the code: > >> o = s.query(T).get(2) >> o.id = 10 >> o.description = "Changed" >> s.flush() > > With autocommit=True, I've always thought flushes created their own > transactions, like so: > > s.begin() > s.flush() > s.commit() > > But if that was true, then the commit happens after the flush. How > would the commit expire anything and/or make anything unreachable for > the flush ? The commit is expiring because that's what it does when expire_on_commit is True.So the flush goes into its post-commit accounting, it in fact has to reload all the objects, one at a time, so is hugely inefficient and I'm going to add a big warning for that in 0.7, ticket 2041. >> >> > > -- > 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. > -- 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.
Re: [sqlalchemy] Re: Strange ObjectDeletedError
I never did understand the pros or cons of running autocommit=True, aside from this flushing issue. Are there performance implications ? On Mon, Feb 7, 2011 at 1:22 PM, Michael Bayer wrote: > I actually just did a little bit of reverse course on this in 0.7. I've > moved all the accounting into the try/except block so that the flush > completes fully before the autocommit expires everything. This is a change > to a pattern that's been the same way since 0.4 so hoping nothing bad happens > when we put 0.7 out into betas. > > > On Feb 7, 2011, at 2:52 PM, Romy Maxwell wrote: > >> Are there any downsides to setting expire_on_commit=False when using >> autocommit=True ? In other words, should I expect to see stale data or >> other side effects ? >> >> On Mon, Feb 7, 2011 at 8:30 AM, Michael Bayer >> wrote: >>> >>> On Feb 7, 2011, at 7:42 AM, Romy Maxwell wrote: >>> Hey Michael, I didn't wanna revive a really old thread [http://www.mail-archive.com/sqlalchemy@googlegroups.com/msg16598.html], so I figured maybe you won't mind the email. I don't understand why, in the thread, using autocommit=True makes the object unreachable, or what that actually means. I'm assuming it was referring to the latter part of the code: > o = s.query(T).get(2) > o.id = 10 > o.description = "Changed" > s.flush() With autocommit=True, I've always thought flushes created their own transactions, like so: s.begin() s.flush() s.commit() But if that was true, then the commit happens after the flush. How would the commit expire anything and/or make anything unreachable for the flush ? >>> >>> >>> The commit is expiring because that's what it does when expire_on_commit is >>> True. So the flush goes into its post-commit accounting, it in fact has >>> to reload all the objects, one at a time, so is hugely inefficient and I'm >>> going to add a big warning for that in 0.7, ticket 2041. >>> >>> >>> > > -- 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.
Re: [sqlalchemy] Re: Strange ObjectDeletedError
I actually just did a little bit of reverse course on this in 0.7. I've moved all the accounting into the try/except block so that the flush completes fully before the autocommit expires everything. This is a change to a pattern that's been the same way since 0.4 so hoping nothing bad happens when we put 0.7 out into betas. On Feb 7, 2011, at 2:52 PM, Romy Maxwell wrote: > Are there any downsides to setting expire_on_commit=False when using > autocommit=True ? In other words, should I expect to see stale data or > other side effects ? > > On Mon, Feb 7, 2011 at 8:30 AM, Michael Bayer > wrote: >> >> On Feb 7, 2011, at 7:42 AM, Romy Maxwell wrote: >> >>> Hey Michael, >>> >>> I didn't wanna revive a really old thread >>> [http://www.mail-archive.com/sqlalchemy@googlegroups.com/msg16598.html], >>> so I figured maybe you won't mind the email. >>> >>> I don't understand why, in the thread, using autocommit=True makes the >>> object unreachable, or what that actually means. I'm assuming it was >>> referring to the latter part of the code: >>> o = s.query(T).get(2) o.id = 10 o.description = "Changed" s.flush() >>> >>> With autocommit=True, I've always thought flushes created their own >>> transactions, like so: >>> >>> s.begin() >>> s.flush() >>> s.commit() >>> >>> But if that was true, then the commit happens after the flush. How >>> would the commit expire anything and/or make anything unreachable for >>> the flush ? >> >> >> The commit is expiring because that's what it does when expire_on_commit is >> True.So the flush goes into its post-commit accounting, it in fact has >> to reload all the objects, one at a time, so is hugely inefficient and I'm >> going to add a big warning for that in 0.7, ticket 2041. >> >> >> -- 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.
[sqlalchemy] Re: Strange ObjectDeletedError
On Oct 5, 4:59 am, Michael Bayer wrote: > On Oct 4, 2009, at 7:54 PM, Y3s wrote: > > > Session = orm.sessionmaker(autocommit=True, autoflush=False) > > you're using non-default session settings, all attributes are expired > upon transaction commit which in this case due to autocommit makes the > object unreachable within the flush, so set expire_on_commit=False > along with your autocommit=True. > Thank you! --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
[sqlalchemy] Re: Strange ObjectDeletedError
On Oct 4, 2009, at 7:54 PM, Y3s wrote:
> Session = orm.sessionmaker(autocommit=True, autoflush=False)
you're using non-default session settings, all attributes are expired
upon transaction commit which in this case due to autocommit makes the
object unreachable within the flush, so set expire_on_commit=False
along with your autocommit=True.
> e = create_engine("sqlite:///")
> m.bind = e
> Session.configure(bind=e)
> m.create_all()
>
> # Insert objects...
> s = Session()
> for x in range(1, 6):
>t = T()
>t.id = x
>t.description = "Object %s" % x
>s.add(t)
> s.flush()
>
> # ...now try to change the ID of one of them...
> o = s.query(T).get(2)
> o.id = 10
> o.description = "Changed"
> s.flush()
--~--~-~--~~~---~--~~
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