there's a specific way that I've been trying to deprecate for years, sure, send 
weak_identity_map=False to the Session constructor.   

If it were me, I'd use an on_load event and just stick each object into a 
dictionary associated with the Session.




On May 22, 2013, at 12:11 PM, Etienne Rouxel <rouxel.etie...@gmail.com> wrote:

> I would like that no garbage collection occurs within a session, is there a 
> way to configure that behavior?
> 
> Le mardi 21 mai 2013 17:31:10 UTC+2, Etienne Rouxel a écrit :
> Hello
> In my program, I was trying to guess why so many SQL queries were sent while 
> some could have been avoided with the help of the identity map.
> So, I reduced my program to what is below and wrote 3 times the same 
> query.get call and 3 SQL queries were sent to the database server.
> Why does SQLAlchemy send 3 times the SQL while it could have done it only 1 
> time for the first call and use the identity map for the 2 last calls?
> 
> from sqlalchemy import *
> from sqlalchemy.orm import *
> from sqlalchemy.ext.declarative import declarative_base
> Base = declarative_base()
> 
> _descriptiontype_table = Table('descriptiontype', Base.metadata,
>         Column('id', Integer, primary_key=True),
>         Column('refno', Integer),
>         Column('sortindex', Integer),
>         Column('designation', String),
>         schema='botany'
>     )
> 
> class Descriptiontype(Base):
>     __table__ = _descriptiontype_table
> 
> if __name__ == '__main__':
> 
>     engine = create_engine('postgresql://user@localhost:5432/mydatabase')
>     Session = sessionmaker(bind=engine)
>     session = Session()
> 
>     session.query(Descriptiontype).get(-2147483648)
>     session.query(Descriptiontype).get(-2147483648)
>     session.query(Descriptiontype).get(-2147483648)
> 
> 
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