Hello again,
I have recently noticed that a particular assignment seems to be taking a "relatively" long time. Not being a database expert I am confused as to whether the last assignment 'person.tags = tags' should be so slow when referencing existing tags that are used by other entities - it seems to try and get a list of all employees that use the given tag and then spends the time doing something with the resulting set, but why? Test case below. If the slow assignment is expected do you have any advice on how to speed up such a statement? Thank you in advance, Martin ---------------------------------------------------------------------------------- import os, datetime, time from sqlalchemy import * from sqlalchemy.orm import * file = '/tmp/test.db' if os.path.isfile(file): os.remove(file) engine = create_engine('sqlite:///%s' % file, echo=True) metadata = MetaData() Session = scoped_session(sessionmaker(autoflush=True, transactional=False, bind=engine)) mapper = Session.mapper # Classes #---------------------------------------------- class Employee(object): def __init__(self, name=None): self.name = name def __repr__(self): return '%s:%s' % (self.id, self.name) class Tag(object): def __init__(self, label): self.label = label # Setup tables #---------------------------------------------- employees = Table('employees', metadata, Column('id', Integer, primary_key=True), Column('name', String, nullable=False, default='bob'), Column('dob', DateTime, nullable=False, default=datetime.datetime.now), ) tags = Table('tags', metadata, Column('id', Integer, primary_key=True), Column('label', String, nullable=False), ) employeesTags = Table('employeesTags', metadata, Column('employee_id', Integer, ForeignKey('employees.id')), Column('tag_id', Integer, ForeignKey('tags.id')), ) # Mappers #---------------------------------------------- mapper(Employee, employees, properties={ 'tags': relation(Tag, secondary=employeesTags, backref='employees', lazy=False) }) mapper(Tag, tags) # Test #---------------------------------------------- metadata.create_all(engine) session = Session() session.begin() tags = [] for i in xrange(20): tag = Tag(str(datetime.datetime.now())) tags.append(tag) for i in xrange(1000): p = Employee('john%d' % i) p.tags = tags session.commit() session.clear() session.begin() tags = session.query(Tag).all()[:2] person = Employee('bob') started = time.time() person.tags = tags print 'Took:', time.time()-started session.commit() session.clear() Session.remove() --~--~---------~--~----~------------~-------~--~----~ 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 [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---