if I might make a suggestion - why are negative numbers being used as surrogate primary key values ?
I don't believe there's any restriction in SQLAlchemy as to this, but it seems a bit suspect. On May 21, 2013, at 2:13 PM, Etienne Rouxel <rouxel.etie...@gmail.com> wrote: > @Charlie Clark: > In the documentation > (http://docs.sqlalchemy.org/en/rel_0_8/orm/session.html#session-frequently-asked-questions > see "Is the Session a cache ?"), it is mentioned that it does not > necessarily performs a query. > > @Simon King: > I guess you're the King indeed, I tried: > 1. to assign the result of the 3 queries to 3 different variables > 2. to assign the result of the 3 queries to the same variable > 3. to assign the result of the first query to a variable and not to assign > the result of the 2 last queries > In all these cases, only 1 SQL query were sent so your suspicion looks > correct. > > Thank you both. > > 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) > > > -- > 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?hl=en. > For more options, visit https://groups.google.com/groups/opt_out. > > -- 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?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
