[sqlalchemy] objects not necessarily pulled from session's identity map when they should (?)
I've been going batty on this all morning. I have a permissions check routine that repeatedly queries for a certain Foo2Bar table class Foo2Bar(Base): __tablename__ = 'foo_2_bar' id_foo = Column(Integer, ForeignKey(foo.id), primary_key=True) id_bar = Column(Integer, ForeignKey(bar.id), primary_key=True) print Get Foo2Bar() 4x print id(s.query(Foo2Bar).get((1,2))) print id(s.query(Foo2Bar).get((1,2))) print id(s.query(Foo2Bar).get((1,2))) print id(s.query(Foo2Bar).get((1,2))) When I do this on a test harness, it works exactly like it should. It only hits the database once. When I do this in my app, it hits the database (postgres) unreliably. I set up extensive logging and used a bunch of breakpoints with pdb. The session is the same at every point, there is an object already in the identity map for the composite key -- but it appears to get overridden each time. If i put a `get()` in a loop 40x, it only gets the first one. but every prior request is pulled from the database. does anyone have a clue what could cause this behavior? -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
Re: [sqlalchemy] objects not necessarily pulled from session's identity map when they should (?)
On Tue, Nov 4, 2014 at 3:15 PM, Jonathan Vanasco jvana...@gmail.com wrote: I have a permissions check routine that repeatedly queries for a certain Foo2Bar table class Foo2Bar(Base): __tablename__ = 'foo_2_bar' id_foo = Column(Integer, ForeignKey(foo.id), primary_key=True) id_bar = Column(Integer, ForeignKey(bar.id), primary_key=True) print Get Foo2Bar() 4x print id(s.query(Foo2Bar).get((1,2))) print id(s.query(Foo2Bar).get((1,2))) print id(s.query(Foo2Bar).get((1,2))) print id(s.query(Foo2Bar).get((1,2))) When I do this on a test harness, it works exactly like it should. It only hits the database once. When I do this in my app, it hits the database (postgres) unreliably. ... does anyone have a clue what could cause this behavior? The code as shown, would likely exhibit that behavior with a weak identity map. It would indeed be hard to predict when it happened since weakrefs are cleared on garbage collection cycles, and those happen at hard to predict times. You could rule that out, by storing the result of get() in some variable somewhere for the duration of the test/routine. That should keep it in the identity map long enough to serve your purposes. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
Re: [sqlalchemy] objects not necessarily pulled from session's identity map when they should (?)
Thanks! I didn't realize that objects are cleaned up with scope like normal python objects. I thought they were in the session for the lifetime of the session. This was driving me crazy. This is just a web request, so I'm now appending the result into `request.persistanceArray`. instantly fixed my problem. -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
